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Title: Chemistry Study Material
Description: Best Chemistry Study Material Issued by Central Board Of Secondary Education (CBSE) For Class 12th................I Hope This Material is useful for you.........Thank you...........& All the Best for your studies..
Description: Best Chemistry Study Material Issued by Central Board Of Secondary Education (CBSE) For Class 12th................I Hope This Material is useful for you.........Thank you...........& All the Best for your studies..
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2014 – 2015
Sl
...
Name
Designation
1
...
B
...
S
...
No
...
Dr
...
Co-ed SSS, Shivpuri,
Delhi-110051
3
...
P
...
V
...
Ravinder Malik
Member
Lecturer (Chemistry),
S
...
V
...
No
...
The Solid State
11-19
2
...
Electrochemistry
23
31-41
4
...
Surface Chemistry
52-58
6
...
The p- Block Elements
66-88
8
...
Co-ordination Compounds
109-116
10
...
Alcohols, Phenols and Ethers
137-150
12
...
Amines
28
173-185
14
...
Polymers
193-197
16
...
Two Solved Practice Papers with Marking Schemes and
Two Unsolved Sample Papers
...
043)
Time : 3 hours
Sl
...
Typology of Questions
Max
...
Remembering – (Knowledge based
Simple recall questions, to know
specific facts, terms, concepts,
principles, or theories; Identify,
define, or recite, information)
2
1
1
2
...
Application – (Use abstract
information in concrete situation, to
apply knowledge to new situations;
Use given content to interpret a
situation, provide an example, or
solve a problem)
-
4
...
Evaluation and Multi-Disciplinary
– (Appraise, judge, and/or justify the
value or worth of a decision or
outcome, or to predict outcomes
based on values)
TOTAL - 2 Projects
SA-II Value based
(3M)
question
(4M)
(LA)
(5M)
Total
Marks
-
-
7
10%
4
-
1
21
30%
2
4
-
1
21
30%
2
-
1
-
1
10
14%
1
-
2
1
-
11
10%
5×1=5 5×2=10 12×3=36 1×4=4 3×5=15 70(26)
3
%
Weightage
100%
[Class XII : Chemistry]
QUESTION WISE BREAK-UP
Type of Question
Mark per Question
Total No
...
Internal Choices : There is no overall choice in the paper
...
2
...
Suitable internal variations may be made for
generating similar templates keeping the overall weightage to different form of questions
and typology of questions same
...
Calculation of number of particles / atoms / ions in a Unit Cell :
Type of
Unit Cell
Number of
particles per
Unit Cell
Relationship
between edge
length (a) and
radius (r) of
atom/ion
Simple cubic (SC)
a = 2r
Body centred cubic (BCC)
2
a =
Face centred cubic (FCC)
2
...
of atoms per unit cell), M is molar mass/
atomic mass, ‘a’ is edge length of the cube, ‘a3’ is volume of cubic unit cell
and NA is Avogadro constant
...
Packing efficiency, PE
4 3
r
3
100
a3
Here ‘M’ is molar mass ‘r’ is radius of atom, ‘d’ is density and NA is
Avogaodro’s constant (6
...
Rank of unit cell can be computed by packing efficiency value
Type of
Unit Cell
Packing
efficiency
Rank of
Unit Cell (Z)
SC
52
...
%
2
FCC
74%
4
5
[Class XII : Chemistry]
Solution
1
...
Molarity (M) =
Moles of solute
mol L–1
Volume of solution in litres
3
...
Parts per million (ppm)
=
5
...
pA° and pB° are vapour pressures
of pure components ‘A’ and ‘B’ respectively
...
Raoult’s law for a solution of non-volatile solute and volatile solvent :
pA ° –pA
n
W MA
= ixB i B = i B
nA
MB WA
pA °
(for dilute solutions)
Where xB is mole fraction of solute, i is van’t Hoff factor and
pA °–pA
is
pA °
relative lowering of vapour pressure
...
Elevation in boiling point (Tb) :
Tb = i
...
Tb = Boiling point of solution
...
8
...
Kf m
where Tf = Tf° – Tf
Kf = molal freezing point depression constant
m = molality of solution
...
Tf = Freezing point of solution
...
Osmotic pressure () of a solution :
V = inRT or
where
= i CRT
= osmotic pressure in bar or atm
V = volume in litres
i = van't Hoff factor
C = molar concentration in moles per litres
n = number of moles of solute
T = Temperature on kelvin Scale
R = 0
...
0821 L atm mol–1 K–1
10
...
11
...
p
...
Conductivity (k) :
k=
1 1 l
= ×
R A
Where R is resistance, l/A = cell constant (G*) and is resistivity
...
Relationship between k and m
m =
1000 k
c
Where m is molar conductivity, k is conductivity and C is molar
concentration
...
(b)
Degree of dissociation () is given by :
=
c
m
om
Here cm is molar conductivity at the concentration C and °m is
limiting molar conductivity of the electrolyte
...
Nernst Equation for electrode reaction : Mn+ (aq) + ne– M(s)
...
303 RT
1
0
...
c
E
d
0
...
2
...
303RT
0
...
Ecell is standard cell polential
...
303 RT log K c
9
[Class XII : Chemistry]
Chemical Kinetics
1
...
(b)
R
t1 =
2k
2
t1 2 is half life period of zero order reaction
...
Integrated rate law equation for first order reaction
(a)
2
...
(b)
Half life period
t1 =
2
3
...
693
k
Arrhenius equation
(a)
k=Ae
–
Ea
RT
Where ‘A’ is frequency factor, Ea is the energy of activation, R is
universal gas constant and T is absolute temperature
...
log k log A –
Ea
Ea
, Here –
is slope of the straight line
2
...
303 R
obtained by plotting log k vs
(b)
k
E
1
T
T –T
a
2
2
1
log k = 2
...
10
[Class XII : Chemistry]
Unit 1
THE SOLID STATE
Points to Remember
1
...
e
...
is 12
...
2
...
3
...
4%, in bcc arrangement
is 68% and in fcc is 74%
...
Unoccupied spaces in solids are called interstitial voids or interstitial sites
...
Two types of interstitial voids are :
(i)
tetrahedral void
(ii)
octahedral void
* No
...
* No
...
6
...
Interstitial defect increases the density of a crystal
...
Point defects in the ionic crystal may be classified as :
(a)
Stoichiometric defect also known as intrinsic or thermodynamic
defect
...
(b)
In non-stoichiometric defect ratio of cations to anions is the different
in defective crystal from the ideal crystal
...
11
[Class XII : Chemistry]
9
...
of cations and anions
from lattice sites in the crystalline solid of the type A + B– and it lowers
and density of crystal of alkali metal halides, e
...
, NaCl, KCl etc
...
Frenkel defect is the combination of vacancy and interstitial defects
...
Density remains the same in Frenkel defect
...
11
...
(b)
Metal excess defect due to presence of extra cations
...
12
...
g
...
13
...
* n-type semiconductors : Silicon or Germinium (group-14) doped with
electron rich impurity (group-15 element like P or As), Here conductivity
is due to the extra electrons or delocalized electrons
...
* 13-15 group compounds, e
...
, InSb, AlP, GaAs
* 12-16 group compounds, e
...
, ZnS, CdS, CdSe, HgTe
...
12
[Class XII : Chemistry]
14
...
Examples are O 2, Cu2+, Fe3+, Cr3+ which are paramagnetic due to the
presence of unpaired one or more electrons
...
*
Diamagnetic substances are weakly repelled by a magnetic field
...
VSA QUESTIONS (1 - Mark Questions)
1
...
Why are amorphous solids isotropic in nature?
3
...
’
4
...
5
...
If the formula of a compound is A2B, which sites would be occupied by A
ions?
[Hint
...
What is the coordination number for
(a)
an octahedral void?
(b)
a tetrahedral void?
8
...
Arrange simple cubic, bcc and fcc lattice in decreasing order of the fraction
of the unoccupied space
...
How much space is empty in a hexagonal closed packed solid?
11
...
Will the
two structures have the same density? Justify your answer
...
]
13
[Class XII : Chemistry]
12
...
Determine the formula of corundum
...
Which point defect is observed in a crystal when a vacancy is created by
an atom missing from a lattice site?
14
...
15
...
Name the crystal defect which lowers the density of an ionic crystal
...
Solid A is very hard, electrical insulator in solid as well as in molten state
and melts at extremely high temperature
...
Which point defect in ionic crystal does not alter the density of the
relevant solid?
19
...
20
...
What type of substances would make better permanent magnets,
ferromagnetic or ferrimagnetic? and why?
22
...
How many atoms constitute one unit cell of a fcc crystal?
24
...
” How?
25
...
List four points of distinctions between crystalline and amorphous solids
...
Mention the suitable reason for the following:
(a)
Ionic compounds are hard and brittle
...
3
...
4
...
14
[Class XII : Chemistry]
(b)
Window glass panes of old buildings are thicker at the bottom than
at the top
...
What is packing efficiency? Calculate the packing efficiency in body-centred
cubic crystal?
6
...
What do you understand by the following types of stacking sequences :
(a) ABAB
...
How are the following properties of crystals affected by Schootky and
Frenkel defects?
(a)
9
...
Density
(b)
In terms of band theory, what is the difference between
(a)
conductor and insulator
(b)
10
...
conductor and semiconductor?
Explain the terms :
(a)
Intrinsic semiconductor
(b)
Extrinsic semiconductor
...
Explain how vacancies are introduced in a solid NaCl crystal when divalent
cations (M2+) are added to molten NaCl
...
What is meant by non-stoichiometric defect? Ionic solids which have anion
vacancies due to metal excess defect develop colour
...
13
...
Mention the main difference between
stoichiometric and non-stoichiometric point defects
...
Define F-centre
...
15
...
solution
...
16
...
17
...
Write the relationship between atomic radius (r) and edge length (a) of
cubic unit cell for
(a)
(b)
Body-centred cubic unit cell
(c)
2
...
group 13 element,
group 15 element
...
(b)
(b)
Antiferromagnetism
13-15 compounds
Examine the defective crystal lattice given below and answer the following
questions :
(a)
(b)
Out of AgCl and NaCl, which is most likely to show this type of defect
and why?
(c)
5
...
Why this defect is also known as dislocation defect?
(a)
What type of semiconductor is obtained when silicon is doped with
Boron?
(b)
What type of magnetism is shown in the following alignment of
magnetic moments of domains of ions?
(c)
What type of point defect is produced when AgCl is doped with
CdCl 2?
16
[Class XII : Chemistry]
NUMERICALS
UNIT CELLS AND CRYSTAL LATTICES
1
...
If
one atom of A is missing from its position at the corner, what is the formula
of the compound?
[Ans
...
A compound made up of elements ‘A’ and ‘B’ crystallises in a cubic close
packed structure
...
What is the formula of the compound?
[Ans
...
In a crystalline solid, anions ‘C’ are arranged in cubic close packing, cations
‘A’ occupy 50% of tetrahedral voids and cations ‘B’ occupy 50% of octanedral
voids
...
: A2BC2]
4
...
What is the
formula of magnetite?
[Ans
...
Sodium crystallises in a bcc unit cell
...
6 g of sodium? Given that the atomic mass of sodium is 23
g mol–1
...
: 6
...
An element crystallises in a cubic close packed structure having a fcc unit
cell of an edge 200 pm
...
[Ans
...
6 g cm–3]
7
...
Edge length of unit cell
is 2
...
The density of the metal is 7
...
Calculate
(a)
The volume of unit cell
...
(c)
Number of atoms in 100 g of metal
...
: (a) 2
...
72 × 10–22 g, (c) 1
...
Molybednum has atomic mass 96 g mol–1 with density 10
...
The
17
[Class XII : Chemistry]
edge length of unit cell is 314 pm
...
(Given NA = 6
...
[Ans
...
95 g cm–3
...
mass of Cu = 63
...
02 × 1023 mol–1]
[Ans
...
z
Calculate packing efficiency by
Z
a3
4 3
r 100
3
a3
using value of
...
10
...
5Å and 3
...
Calculate the ratio of the density of fcc
to bcc lattices
...
Tungsten crystallizes in body centred cubic unit cell
...
5pm, calculate the radius of tungsten atom?
[Ans
...
04 pm]
12
...
65 pm
...
874 g cm–3
...
(At
...
845u)
...
: 6
...
Silver crystallizes in fcc unit cell
...
Calculate radius of the silver atom
...
An element with density 11
...
Calculate atomic mass of element
...
AgCl is doped with 10–2 mol% of CdCl2, find the concentration of cation
vacancies
...
: 10–4 mol]
18
[Class XII : Chemistry]
16
...
02 x 1016 mol–1
...
The composition of a sample of Wustite is Fe0
...
00
...
: 15
...
Tina took Sheena to her ancestral house in a village
...
Both observed that glass panes fixed to windows were
thicker at the bottom than at the top
...
(a)
(b)
Why were some glass objects milky in appearance?
(c)
19
...
They were asked to arrange them in an orderly manner in
minimum time
...
(a)
Tell the method of packing of balls by successful group of students
...
LONG ANSWER QUESTIONS (5-Mark Questions)
20
...
(3)
(b)
What is the effect of temperature on conductivity of metals,
semiconductors and insulators?
(2)
21
...
(iii)
(b)
Ferrimagnetic substances
...
(1+1+1)
Calculate packing efficiency for BCC unit cell
...
The component that is present in the larger amount is known as solvent
...
Water is an universal
solvent
...
Mole fraction (x) is a unitless quantity
...
Molality(m) and mole fraction are temperature independent quantities,
whereas molarity decreases with increase in temperature
...
As the temperature increases Henary’s law constant, KH increases so the
lower is the solubility of the gas in the liquid
...
11
...
6
...
e
...
7
...
8
...
Maximum
boiling azeotropes form when solutions exhibit negative deviation from
Raoult’s law whereas minimum boiling azeotropes form when solutions
exhibit positive deviation from Raoult’s law
...
Relative lowering in vapour pressure is a colligative property but lowering
in vapour pressure is not
...
van’t Hoff factor (i ) is the ratio of the observed value of the colligative
property in solution to the theoretically calculated value of the colligative
property
...
(b)
A non-volatile solute undergoes association then i < 1
...
Two solutions having same osmotic pressure at a given temperature are
called isotonic solutions
...
9% (mass/volume) sodium chloride (called
saline solution) is isotonic with the fluids inside the blood cell
...
A solution which has higher osmotic pressure is called hypertonic solution
while the other solution with lower osmotic pressure is known as hypotonic
solution
...
Semipermeable membrane (SPM) can allow to pass through it only solvent
molecules and not the solute molecules
...
Give an example of ‘liquid in solid’ type solution
...
Which type of solid solution will result by mixing two solid components with
similar sizes of their molecules?
3
...
What will be the mole fraction of water in C2H5OH solution containing
equal number of moles of water and C2H5OH?
5
...
10 g glucose is dissolved in 400 g
...
Calculate percentage
concentration (mass/mass) of the solution
...
Gases tend to be less soluble in liquids as the temperature is raised
...
State the conditions which must be satisfied if an ideal solution is to be
formed
...
: Vmix = 0, Hmix = 0 and Raoults law is obeyed]
9
...
Why?
10
...
N2 and O2 gases have KH values 76
...
86 kbar respectively
at 293 K temperature
...
Under what condition molality and molarity of a solution are identical
...
[Ans
...
Addition of HgI2 to KI (aq
...
Why?
14
...
Liquid ‘Y’ has higher vapour pressure than liquid ‘X’, which of them will
have higher boiling point?
*16
...
Justify
your answer
...
Which type of deviation is shown by the solution formed by mixing
cyclohexane and ethanol?
18
...
Which type of deviation
from Raoult’s law is there?
[Ans
...
Define cryoscopic constant (molal freezing point depression constant)
...
Mention the unit of ebulioscopic constant (molal boiling point elevation
constant)
...
If kf for water is 1
...
1 molal
solution of a substance which undergoes no dissociation or association of
solute?
22
...
*23
...
10H2O?
24
...
25
...
The phase diagram for pure solvent and the solution containing nonvolatile
solute are recorded below
...
AgNO3 on reaction with NaCl in aqueous solution gives white precipitate
...
in the side ‘X’ due to osmosis?
[Ans
...
Explain the following :
(a)
(b)
2
...
Ionic compounds are soluble in water but are insoluble in nonpolar
solvents
...
(b)
showing negative deviation from Raoult’s Law
...
Draw vapour pressure vs composition (in terms of mole fraction) diagram
for an ideal solution
...
Define azeotropes with one example of each type
...
Draw the total vapour pressure vs
...
6
...
The curves are parallel to each
other and do not intersect
...
1 bar
23
[Class XII : Chemistry]
7
...
8
...
9
...
10
...
11
...
Which
solute will show greater elevation in boiling point and Why?
12
...
13
...
Molecular masses of polymers are determined by osmotic pressure
measurement method and not by measuring other colligative properties
...
15
...
16
...
What is the effect of temperature on the solubility of a
gas in a liquid?
17
...
24
[Class XII : Chemistry]
(b)
How it get affected by change in temperature
...
Given reason for the following :–
(a)
Aquatic species are more comfortable in cold waters than in
warm waters
...
(c)
Cold drinks bottles are sealed under high pressure of CO2
...
Why should a solution of a non-volatile and non-eletrolyte solute boil at a
higher temperature? Explain with the help of a diagram
...
3
...
(b)
Ethylene glycol is used as antifreeze in radiators of vehicles in cold
countries
...
01 m NaCl is nearly twice that of
0
...
4
...
5
...
1% NaCl solution
...
25
[Class XII : Chemistry]
6
...
1 m NaCl, 0
...
1 m MgCl2
(c)
0
...
1 m sucrose, 0
...
pt
...
pt
...
What are ideal solutions? Write two examples
...
0 g of polymer of molar mass 185000 in
450 mL of water at 27°C
...
314 J mol–1k–1)
...
: 1
...
(b)
2
...
mass 60 g mol–1) must be dissolved in 50 g
of water so that the vapour pressure at the room temperature is
reduced by 25% ? Also calculate the molality of the solution obtained
...
: 55
...
5 m]
3
...
86 Km–1
...
(c)
Calculate the amount of ice that will separate out on cooling solution
containing 50 g of ethylene glycol (molar mass = 62 g mol–1) in 200
g H2O to –9
...
(Kf for water = 1
...
: 38
...
(a)
Define osmotic pressure
...
2 atm at normal body temperature of 37°C?
[Ans
...
283 M]
26
[Class XII : Chemistry]
NUMERICAL PROBLEMS
EXPRESSING CONCENTRATION OF SOLUTIONS
1
...
[Ans
...
3%, CCl4 = 84
...
Calculate (a) molality (b) molarity and mole fraction of KI if the density of
20% (mass/mass) aqueous KI is 1
...
[Ans
...
5 m, (b) = 1
...
0263]
3
...
011 × 10 Cl– ions
...
Assume that calcium chloride is completely
ionized
...
: 0
...
A bot l of com m erci H 2SO4
te
al
[density = 1
...
(a)
What is the molarity of the acid?
(b)
What volume of the acid has to be used to make 1 litre 0
...
: 15
...
74 mL, 62
...
The maximum allowable level of nitrates in drinking water is 45 mg nitrate
ions/dm3
...
: 45 ppm]
6
...
Calculate the ppm of
oxygen in sea water
...
: 6 ppm]
HENRY’S LAW
7
...
35 × 10–3 mol L–1 at 20°C and 1 atm
pressure
...
2 atm
pressure
...
: 2
...
If O2 is bubbled through water at 393 K, how many millimoles of O2 gas
would be dissolved in 1L of water? Assume that O2 exerts a pressure of
0
...
(Given KH for O2 = 46
...
9
...
67 × 108 pa at 298
K
...
5 atm of CO2 pressure at 298K
...
3
...
Benzene and toluene form a nearly ideal solution
...
[Given : p°Benzene = 150 mm of Hg, p°Toluene = 55 mm of Hg]
11
...
Find out the composition of the liquid mixture if total
vapour pressure is 600 mm Hg
...
[Ans
...
4, XB = 0
...
3, YB = 0
...
Two liquids X and Y on mixing form an ideal solution
...
But
when 4 mol of X and 1 mol of Y are mixed, the vapour pressure of solution
thus formed is 560 mm Hg
...
: px = 600 mm Hg; py = 400 mm Hg]
13
...
Determine the vapour pressure of an
aqueous solution containing 10% by mass of urea at 40°C
...
3 mm Hg)
[Ans
...
53 mm Hg]
RELATIVE LOWERING IN VAPOUR PRESSURE
14
...
8 kPa at 298 K
...
9 kPa at 298 K
...
[Ans
...
4 kPa]
15
...
004
bar at the normal boiling point of the solvent
...
: 41
...
At 25°C, the saturated vapour pressure of water is 3
...
75 mm
Hg)
...
[Molar mass of urea = 60
...
[Ans
...
115 KPa]
17
...
[Ans
...
0 g]
28
[Class XII : Chemistry]
ELEVATION IN BOILING POINT
18
...
01°C
...
5 K kg
mol–1
...
[Ans
...
2 × 1021 molecules]
19
...
12 g of barium chloride in 250 g of water
is found to boil at 100
...
Calculate the degree of dissociation of
barium chloride
...
52 K/m]
[Ans
...
3%]
20
...
At what temperature will this solution boil?
[Kb for water = 0
...
15 K)
[Ans
...
202 K]
DEPRESSION IN FREEZING POINT
21
...
0 g of an unknown molecular substance was dissolved in 450 g of
water
...
34°C
...
(Kf for water = 1
...
22
...
62 K
...
9 K kg mol–1
...
: 99
...
75
...
[Ans
...
Calculate the amount of NaCl which must added to one kg of water so that
the freezing point is depressed by 3K
...
86 K kg mol–1, Atomic
mass : Na = 23, Cl = 35
...
[Ans
...
81 mol NaCl]
25
...
6 mL of acetic acid (CH3COOH) having density 1
...
The depression in freezing point observed for this strength
of acid was 0
...
Calculate the van’t Hoff Factor (i)
...
Two elements A and B from Compounds having formula AB2 and AB4
...
0 g benzene (C6H6), 1 g and AB2 lowers the freezing
point by 2
...
0 g of AB4 lowers it by 1
...
The molar depression
constant for benzene is 5
...
Calculate atomic masses of A
and B
...
: A = 25
...
644]
27
...
48 K
(Kf = 5
...
OSMOTIC PRESSURE
28
...
877% solution of
urea
...
[Ans
...
99 g mol–1]
29
...
0103 molar solution of an electrolyte was found
to be 0
...
Calculate van’t Hoff factor
...
: i = 3]
VALUE BASED QUESTIONS (4-MARK QUESTIONS)
30
...
Yamini observed that her mother
cut mangoes into pieces and then kept them in salt water
...
She goes to her elder
sister and asks about this happening
...
(c)
31
...
The teacher asked Parul to add pure NaCl to warm
water and gargle with it
...
Then her friend
explained the chemistry behind this effect
...
Justify your answer
...
(c)
Write the associated values shown by Parul’s friend and her teacher
...
Electrochemical cells (Galvanic cells) produce electricity as a result of
chemical reactions at the electrodes while in electrolytic cells, electricity
is used to produce a non-spontaneous chemical changes at the
electrodes
...
In Galvanic Cells, oxidation occurs at –ve electrode called anode whereas
reduction occurs at +ve electrode called cathode
...
SHE (Standard Hydrogen Electrode) is represented by Pt/H 2 (g, 1 bar)/
H+(1M) and it is used as a reference half-cell having zero potential
...
0V
4
...
5
...
6
...
Unit : Ohm –1 or S
...
Conductivity (specific conductance) denoted by k, is reciprocal of resistivity
and is expressed in S cm –1
...
Unit of conductivity cell constant is cm –1 or m–1
...
Molar conductance at concern (cm) is conductance of solution containing
1 mol of solute in a given volume
...
Conductivity decreases but molar conductivity increases with decrease in
concentration
...
In electrochemical process, the voltage required for a reaction is
sometimes much greater than that indicated by the electrode potentials
...
31
[Class XII : Chemistry]
12
...
in the cell reaction
...
Corrosion of metals is essentially an electrochemical phenomenon
...
VSA QUESTIONS (1 - MARK QUESTIONS)
1
...
Give the cell representation for Daniell Cell
...
Give the condition for for a cell when there is no flow of electrons or current
...
Can you store zinc sulphate solution in a copper container? Give suitable
reason
...
76V, E Cu2+/Cu = 0
...
Write Nernst equation for the electrode reaction : Mn+(aq) + ne– M(s) at
298 K and 1 bar pressure
...
List the two factors that influence the value of cell potential of a galvaniccell
...
Show the direction of flow of electrons in the following cell :
Zn (s) | Zn2+ (aq) || Ag+ (aq) | Ag (s)
8
...
9
...
Write its SI unit
...
How does specific conductance or conductivity of electrolytic solution vary
with temperature?
11
...
12
...
13
...
14
...
15
...
16
...
32
[Class XII : Chemistry]
17
...
25V and 0
...
Which of these will liberate hydrogen gas from dilute H2SO4?
18
...
19
...
20
...
: Salts present in saline water perform the function of salt-bridge
...
Write the name of a chemical substance which is used to prevent corrosion
...
: Bisphenol]
22
...
Explain why?
2+
2
Given : E Fe / Fe = – 0
...
76V
23
...
34 V and E
0
...
List two points of difference between electrochemical cell and electrolyticcell
...
A conventional method of representing a Daniel cell is :
Zn (s) | Zn2+ (1M) || Cu2+ (1M) | Cu (s)
...
(ii)
Write the reactions taking place at the cathode and the anode during
the operation of Daniel cell
...
List two points of difference between metallic conductance and
electrolytic conductance
...
List two factors which affect the conductivity of ionic solutions
...
Explain the meaning of the terms
(a)
6
...
(b)
Over-voltage
Account for the fact that when chlorine is passed through a fluoride solution,
no reaction takes place
...
87V; E Cl2
2Cl–
Cl
2
–
2Cl = 1
...
Copper does not dissolve in HCl (aq) but dissolves in HNO3 (aq) producing
Cu2+ ions
...
[Given E Cu2+
Cu–
= 0
...
NO
–
2Cl
–
= 1
...
97V]
Explain the following observations :
(a)
The products of electrolysis of molten NaCl are sodium metal and
chlorine gas
...
9
...
10
...
11
...
In a dry cell, the build up of ammonia around the carbon cathode
should disrupt the electric current, but in practice this does not happen
...
The following figure shows two electrolytic cells connected in series
...
: (a) 1F, (b) 2:1]
34
[Class XII : Chemistry]
13
...
Give the plausible reason for the fact :
addition of water is necessary from time to time for maintenance
[Ans
...
Formulate the galvanic cell in which the following reaction takes place :
Zn(s) + 2Ag+ (aq) Zn2+ (aq) + 2Ag(s)
State :
(a)
Which one of its electrodes is negatively charged?
(b)
The reaction taking place at each of its electrode
...
2
...
How is molar conductivity
of a solute related to conductivity of its solution?
3
...
(b)
Molar conductivity of a strong electrolyte like KCl decreases almost
linearly while increasing concentration?
(c)
It is not easy to determine °m of a weak electrolyte by extrapolation
of c s m curve?
4
...
Write
the electrode reactions for this cell
...
(a)
Write the mechanism of the corrosion of metals
...
LONG ANSWER TYPE QUESTIONS (5-MARK QUESTIONS)
1
...
Mention
two applications of this law
...
001M CH3COOH 4
...
Calculate
its dissociation constant
...
5 S cm2
mol–1
...
: = 0
...
(i)
Define molar conductivity
...
3
...
(b)
Silver is deposited on a metallic vessel of surface area 800 cm2 by
passing current of 0
...
Calculate the thickness
of silver deposited
...
47 g cm–3, Molar atomic mass of silver =
107
...
[Ans
...
9 × 10–4 cm]
(a)
Draw the diagram of standard hydrogen electrode
...
(b)
Calculate the equilibrium constant for the reaction :
Fe2+ + Ce4+
Ce3+ + Fe3+
Given E Ce4
1
...
68V
Fe2
[Ans
...
6 × 1012]
5
...
Fuel cell
...
1M KCl solution is 100
...
02M KCl solution is
520 , calculate the conductivity and molar conductivity of
...
The conductivity of 0
...
29 × 10–2 –1
cm–1
...
(a)
State Faraday’s first law of electrolysis
...
(b)
Calculate emf of following cell at 298K
Mg(s) | Mg2+ (0
...
01M) | Cu(s)
...
71 V, 1F=96500 C mol–1
...
For concentration cell :
Cu (s) Cu2+ (0
...
1M) Cu (s)
(a)
Calculate the cell potential
...
2
...
1M solution of ZnSO4
...
Calculate the electrode potential
E
3
...
295V, (b) No
...
76 V
...
: –0
...
34V
...
and the pH of solution
...
: x = 1
...
743]
4
...
1M?
Given E Ag+
0
...
34 V
...
[Ans
...
3 × 10–9]
Write the Nernst equation and calculate the emf of the following cell at
298K
...
130M) || Ag+ (10–2 M) | Ag(s)
Given E
6
...
34 V; E
Cu
0
...
: 0
...
010M) || H+ (0
...
9 bar) | Pt(s)
Given E
[Ans
...
29 V]
–
Br2 |Br |Pt 1
...
Calculate the emf of the cell :
Mg Mg 2 (0
...
001M ) Cu
E Cu 2
Given
0
...
375 V
Mg 2
Mg
[Ans
...
651 V]
8
...
001M H 1M H2 g, 1bar Pt s
E 0
...
: 0
...
Calculate the equilibrium constant for the reaction at 25°C
...
46V
...
314 JK–1 mol–1]
10
...
: 4
...
Cu2+ (aq) + Fe(s) Fe2+ (aq) + Cu(s)
E Cu2+
11
...
34 V; E
Cu
Fe2
0
...
: –150, 540 kJ]
Calculate the standard cell potential of a galvanic cell in which the following
reaction takes place :
2Cr(s) + 3Cd2+ (aq) 2Cr3+ (aq) + 3Cd(s)
Calculate rG and equilibrium constant, K of the above reaction at 25°C
...
74V, E
2
Cd Cr
0
...
[Ans
...
173 × 1034]
12
...
1M) || Cd2+ (0
...
763V, E
Cd2 Cr
0
...
R = 8
...
: Cell emf = 0
...
48 kJ mol–1]
13
...
Given EØ
Zn2+/Zn
= – 0
...
8V
[Ans
...
08 kJ / mol
...
56V]
14
...
(F = 96500 C mol–1]
[Ans
...
720 V]
[Hint :
2
4
Al O Al O2 , r G 1050 kJ / mol
3 2 3
3
rG = –nE F and n = 4]
15
...
[Ans
...
228 V]
[Hint : The Cell reaction is :
2H2 + O2 2H2O ,
rG = 2fG = –2 × 237 kJ mol–1
The number of electorns involved = 4
rG = –n ECell F
...
The conductivity of 0
...
025 S cm–1
...
[Ans
...
The molar conductivity of 0
...
6 S cm2 mol–1
...
39
[Class XII : Chemistry]
18
...
01 M KCl solution at 298K
is 1500
...
001 M KCl
solution at 298K is 0
...
: 0
...
The molar conductivities of NH+4 ion and Cl– ion are 73
...
255 cm2 mol–1 respectively
...
1 M NH4Cl is
1
...
Calculate the dissociation constant of NH4Cl
...
: 7
...
Molar conductivity at infinite dilution for NH4Cl, NaOH and NaCl solution at
298K are respectively 129
...
4 and 108
...
33 S cm2 mol–1
...
[Ans
...
039]
21
...
9 S cm2 mol–1
°m(H+–) = 349
...
7 S cm2 mol–1
[Ans
...
One afternoon when Preeti returned from her school she found that the
main gate of her house was painted in green
...
After about two months, she noticed a brown and brittle solid deposited
at a small portion of the gate
...
Immediately she thought of
its reason
...
(c)
What is role of paint on gate
...
Mention the reason of deposition of brown and brittle solid on thegate
...
Manu and his father went to a shop to purchase a battery for inverter
...
Manu’s father wanted to purchase lead battery
as it was cheaper but Manu suggested cadmium battery
...
40
[Class XII : Chemistry]
(b)
(c)
Write the overall cell reaction when the cell is discharged
...
What are values associated with above decision
...
Explain why?
Using G data calculate the E for the following reaction–
f
cell
Zn (s) + Ag2O (s) + H2O (l) Zn2+ (aq
...
)
Given –
f G in kJ/mol for—
Ag2O (s)
11
...
13
Zn2+ (aq
...
24
r G
=
f G (products) — f G (reactants)
...
21 KJ/mol
...
1047 V
...
Rate constant is equal to rate of reaction when the concentration of each
reactant is taken as 1 mol L –1
...
Order of reaction is the sum of the powers of the concentration terms of
the reactants in the rate law expression
...
It may be zero, whole number or fractional
...
Molecularity is the number of reacting species taking part in an elementary
reaction
...
4
...
5
...
r
...
each of the two reactants, it becomes
pseudo first order when one of the reactants is taken in excess
...
The half life (t1/2) of a reaction is the time in which the concentration of
a reactant is reduced to one half of its initial concentration
...
1
R n–1
0
A catalyst does provide a reaction path of lower activation energy without
affecting the magnitude of equilibrium constant and the enthalpy of
reaction (rH)
...
A collision of correctly oriented particles will be effective if the kinetic
energy of collision is activation energy (E a)
...
Rate of reaction increases exponentially with the rise in temperature as
shown by the equation :
k A e –Ea
RT
10
...
11
...
VSA QUESTIONS (1- MARK QUESTIONS)
1
...
2
...
3
...
For a chemical reaction represented by R P, the rate of reaction is
denoted by
– R
+ P
or
t
t
Why a positive sign (+) is placed before
P
and negative sign (–) before
t
R
?
t
5
...
N2(g) + 3 H2 (g) 2NH3 (g)
6
...
Write the unit of first order rate constant of a gaseous reaction if the partial
pressure of gaseous reactant is given in bar
...
For a reaction :
R P, the change in concentration of reactant w
...
t
...
9
...
10
...
[Ans
...
For a chemical reaction A B
...
What is the value of n?
[Ans
...
13
...
: First order]
*14
...
[Ans
...
A reaction is 50% complete in 2 hours and 75% complete in 4 hours
...
Suggest an appropriate reason for the observation : “On increasing
temperature of the reacting system by 10 degrees, the rate of reaction
44
[Class XII : Chemistry]
almost doubles or even sometimes becomes five folds
...
For a chemical reaction, activation energy is zero at 300K and rate constant
is 5
...
: 5
...
Two reactions occuring at the same temperature have identical values of
activation energy
...
[Hint : Rate depends on the nature and concentrations of reactants and
also pre-exponential factor
...
The rate constant of a reaction is given by the expression k = Ae–Ea/RT
Which factor in this expression should register a decrease so that the
reaction proceeds rapidly?
20
...
3 × 10–4 mol L–1 s–1, what will
be the order of reaction?
[Ans
...
List four factors which affect the rate of a chemical reaction
...
2
...
Average rate and instantaneous rate of a chemical reaction
...
e
...
The rate law for the reaction :
A + B P is given by
Rate = k [A]n [B]m
On doubling the concentration of A and reducing the concentration of B to
half of its original concentration, calculate the ratio of the new rate to the
previous rate of reaction
...
: 2n–m]
4
...
: diminishes to 1/8 of initial value]
45
[Class XII : Chemistry]
5
...
Show that time required for 99
...
7
...
Predict the order from the graphs
...
(a)
For a reaction A + B Products, the rate law is given by
r = k [A]1/2 [B]2
What is the order of reaction?
(b)
the conversion of molecules X to Y follows second order kinetics
...
: (a) 5/2; (b) 9 times]
SA (II) TYPE QUESTIONS (3 - MARK QUESTIONS)
1
...
2
...
(b)
Write one point of difference between rate of reaction and rate
constant
...
Draw a graph between fraction of molecules and kinetic energy of the
reacting species for two different temperatures :
(a)
Room temperature
(b)
Temperature 10°C higher than the room temperature
(c)
Indicate the fraction of additional molecules which react at (t +10)°C
...
(a)
A chemical reaction is of second order w
...
t
...
How will the
rate of reaction be affected if the concentration of this reactant is
(a) doubled; (b) reduced to 1/8th?
[Ans
...
All the measurements were taken
at 263K
Experiment
No
...
15
0
...
60
2
0
...
30
1
...
30
0
...
40
4
0
...
25
?
(i)
Write the expression for rate law
...
(iii)
What is the initial rate of disapperance of Cl2 in exp
...
: (i) Rate = k [NO]2 [Cl2], (ii) k = 177
...
7765 M/min]
2
...
(b)
3
...
Presence of a catalyst lowers the energy of activation by 75%
...
What
would be the units of the first order rate constant if the concentration
is expressed in moles per litre and time in seconds?
(b)
For first order chemical reaction, half-life period (t1/2) is concentration
independent
...
47
[Class XII : Chemistry]
4
...
If the value of A is
4×1010s–1
...
NUMERICAL PROBLEMS
RATE OF REACTION
1
...
03M to
0
...
Calculate the average rate of reaction using unit of
time both in minutes and seconds
...
: 4 × 10–4M min–1, 6
...
For a chemical reaction A B, it was found that concentration of B
increases by 0
...
What is the average rate of
reaction
...
: 0
...
For the reaction
2A + B A2B
the rate = k[A]1[B]2 with k = 2
...
Calculate the initial rate
of reaction when [A] = 0
...
2 mol/L
...
06 mol L–1
...
: (i) 8 × 10–9 mol–2 L2 s–1; (ii) 3
...
The experimental data for the reaction : 2A + B2 2AB, are as follows
...
[A] mol/L–1
[B2] mol/L–1
Initial rate (mol L–1 sec–1)
0
...
5
1
...
5
1
...
2 × 10–4
1
...
0
3
...
The reaction SO2Cl2(g)
SO2(g) + Cl2(g) is a first order reaction
104
with half life of 3
...
What percentage of SO2Cl2 would
be decomposed on heating at 575K for 90 min
...
: 11
...
A first order reaction has a rate constant 1
...
How long will 5g
of this reactant takes to reduce to 3g?
[Ans
...
Show that for a first order reaction, time required for 99% completion is
twice for the time required for the 90% completion of reaction
...
A reaction is 20% complete in 20 minutes
...
[Ans
...
For the decomposition of azoisopropane to hexane and nitrogen at 543K,
the following data are obtained
...
)
0
360
720
Pressure (atm
...
0
54
...
0
[Ans
...
20 × 10–3 s–1]
Calculate the rate constant
...
The rate constant for a chemical reaction is 2
...
If the
initial concentration of reactant is 0
...
[Ans
...
6 × 10–5 mol L–1 min–1; (b) 4
...
20
2
...
303 10
–3
0
...
0191 mol L–1 min–1
Now calculate rate after 20 minutes]
...
For first order decomposition of SO2Cl2
...
Expt
...
)
1
...
0
100
0
...
7
49
[Class XII : Chemistry]
ACTIVATION ENERGY
12
...
The rate constant is 6
...
05 × 105 J mol–1
...
(R = 8
...
[Ans
...
97 × 10–3 s–1]
13
...
5×1011 s–1) e–28000 K/T,
[Ans
...
79 kJmol–1)
Calculate activation energy (Ea)
...
The rate of reaction triples when the temperature changes from 20°C to
50°C
...
[R = 8
...
48]
[Ans
...
59 kJ]
15
...
If the same reaction is
carried out in the presence of a catalyst at the same rate, the temperature
required is 400 K
...
[Hint : k = Ae –Ea/RT
...
In the
presence of catalyst, Ea = (x – 20) kJ mol–1] [Ans
...
The rate constant for the first order decomposition of H2O2 is given by the
following equation : log k = 14
...
25 × 104 K/T
...
[Ans
...
34 kJ; T = 670K]
17
...
Calculate the activation
energy if it is a first order reaction
...
314J K–1 mol–1, log 4 = 0
...
[Ans
...
206 kJ/mol]
Rate constant ‘k’ of a reaction varies with temperature ‘T’ according to the
equation:
log k log A –
Ea 1
2
...
Calculate ‘Ea’ for the
reaction
...
314 J k–1 mol–1]
...
: 81
...
When a graph is plotted for log k vs
50
[Class XII : Chemistry]
VALUE BASED QUESTION (4-Mark Question)
19
...
The teacher
provided zinc granules, zinc powder and dilute H2SO4
...
(a)
In which case the rate of reaction would be faster?
(b)
What is the reason for this?
(c)
What value do you associate with the above
...
Adsorption occurs because of unbalanced forces acting inwards on the
surface of the solid or a liquid
...
The substance adsorbed is called adsorbate and substance on which
adsorption takes place is adsorbent
...
In physical adsorption, adsorbate is held to adsorbent by weak van der
Waals forces
...
4
...
5
...
If it is less on the surface with
respect to bulk it is called negative adsorption
...
Greater the surface area of the adsorbent, the more is the extent
adsorption
...
Higher the critical temperature of a gas, greater is its exent of adsorption
...
Physical adsorption is due to van der Waals forces and is reversible
...
9
...
The lower the temperature, the greater is the effect of pressure
...
Freundlich adsorption isotherm is
x
kP1 n n 1
m
, i
...
,
52
log
x
1
log k log P
m
n
[Class XII : Chemistry]
The plot of log x/m vs log P gives a straight line with slope =
1
and y
n
intercept = log k
...
Adsorption is generally temperature dependent
...
12
...
13
...
In general, a catalyst functions by lowering the
energy of activation which in turn makes the rate constant larger and,
hence, the rate of reaction higher
...
In homogeneous catalysis, the catalyst is in the same phase as are the
reactants and in heterogeneous catalysis, the catalyst is in the different
phase from the reactants
...
Enzymes are biological catalysts
...
4
...
Enzyme catalysed reaction takes place in two steps :
E S ES fast and reversible
[ES] E + P (slow and rate determining)
(E is enzyme, S is subtrate and P is product)
17
...
Their size ranges in the order 1 nm to 1000 nm
...
A colloidal system consists of two phases : the dispresed phase and
dispersion medium
...
Lyophilic sols are formed by organic substances like gum, starch, protein
etc
...
53
[Class XII : Chemistry]
20
...
These are irreversible and less stable
...
The stability of lyophilic sols is due to their greater hydration in the
solution
...
The colloidal systems show Brownian movement, Tyndall effect and
electrical properties
...
Aggregate of ions in an associated colloidal sol is called ionic micelle
...
24
...
25
...
26
...
27
...
28
...
29
...
by the addition of 1 mL of 10% NaCl is called gold
number
...
30
...
These can be of (i) oil in water (o/w) and
(ii) water in oil (w/o) type
...
The process of making emulsion is called emulsification
...
To stabilise an emulsion, an emulsifying agent or emulsifier is added
...
54
[Class XII : Chemistry]
VSA QUESTIONS (1 - Mark Questions)
1
...
Why are adsorbate particles attracted and retained on the surface of
adsorbent?
3
...
4
...
” Illustrate with an example
...
“Adsorbents in finely divided form are more effective
...
Name two compounds used as adsorbent for controlling humidity
...
Mention one shape selective catalyst used to convert alcohol directly into
gasoline
...
‘Generally high temperature is favourable for chemisorption
...
Name the catalyst used in the following process :
(a)
Haber’s process for the manufacture of NH3 gas
...
10
...
11
...
Why are gas masks used by miners in coal mines?
13
...
14
...
15
...
16
...
17
...
Why do colloidal particles show Brownian movement?
[Ans
...
State the sign of entropy change involved when the molecules of a
substances get adsorbed on a solid surface
...
: S = –ve]
55
[Class XII : Chemistry]
20
...
What happens when hydrated ferric oxide and arsenious sulphide sols are
mixed in almost equal proportions?
22
...
Why?
[Hint : Ice-cream is water is oil type (o/w) emulsion and gelatin acts as emulsifier]
...
Mention the two conditions for the formation of micelles
...
: CMC & Tk]
24
...
Which of the following is more effective in coagulating positively charged
hydrated ferric oxide sol : (i) KCl (ii) CaSO4 (iii) K3 [Fe(CN)6]
...
State the purpose of impregnating the filter paper with colloidion solution
...
Mention one use of ZSM–5 catalyst
...
Explain the effect of temperature on the extent of physical and chemical
adsorption
...
Define the term peptization and mention its cause
...
What will be the charge on colloidal solutions in the following cases
...
31
...
Mention two examples of emulsifying agents for o/w type emulsions and
w/o type emulsions
...
Suggest a mechanism of enzyme catalysed reaction
...
A small amount of silica gel and a small amount of anhydrous calcium
chloride are placed separately in two beakers containing water vapour
...
[Hint : Silica gel – Adsorption, Anhydrous CaCl2–Absorption, as it forms
CaCl2
...
Write the two points of difference between adsorption and absorption?
56
[Class XII : Chemistry]
36
...
In what way these are different : (a) a sol and a gel (b) a gel and an
emulsion
...
State “Hardy Schulze Rule” with one example
...
What is an emulsifying agent? What role does it play in forming
an emulsion?
40
...
(a)
In reference to Freundlich adsorption isotherm, write the expression
for adsorption of gases on solids in the form of equation
...
Helmholtz electrical double layer
...
42
...
43
...
Artificial rain can be caused by spraying electrified sand on the clouds
...
Write chemical equations for the preparation of sols :
(a)
(b)
45
...
hydrated ferric oxide sol by hydrolysis
...
oil in water type (o/w) and(b)
water in oil type (w/o)
What are lyophilic and lyphobic colloids? Which of these sols can be easily
coaqulated on the addition of small amounts of electrolytes?
SA (II) TYPE QUESTIONS (3-Mark Questions)
47
...
Write the steps of ‘Modern Adsorption Theory of Heterogenous Catalysis
...
Mention the two important features of solid catalysts and explain with the
help of suitable examples
...
How are the following colloids different from each other in respect of
dispersion medium and dispersed phase? Give one example of each type
...
[Class XII : Chemistry]
51
...
when river water meets the sea water
...
52
...
VALUE BASED QUESTIONS (4-Mark Questions)
53
...
While inserting a glass tube in a rubber cork, a student got a cut on his
finger and started bleeding
...
When
a few drops of ferric chloride were applied on the cut, the bleeding was
stopped
...
(c)
What value can be associated to the above incidence
...
If yes, why?
A factory was situated very close to a residential area where Rahul lived
...
Rahul
and few others decided to meet factory officials and gave them an idea to
install an apparatus in chimney
...
(a)
Define adsorption
...
(iii)
Enthalpy change
...
Reversibility
...
58
[Class XII : Chemistry]
Unit - 6
GENERAL PRINCIPLES AND PROCESSES OF
ISOLATION OF ELEMENTS
Flow-sheet diagram of the metallurgical process is given below
...
Crushing and grinding
Powdered Ore
Step 2
...
(iv) Electrostatic concentration
...
xH2O(s) + NaHCO3(aq)
Heat
Al2O3
...
59
[Class XII : Chemistry]
Concentrated Ore
Stem 3
...
Calcination or Roasting
Note: Absence of air is not necessary
in calcination
...
Purification of the metal
Distillation : Zn, Hg
Liquation : Sn
Electrolytic refining : Cu
Zone refining Ge, Si, B, Ga, ln
Vapour phase refining :
Mond’s process : Ni
Van Arkel Method : Zr, Ti
...
Chromatographic method : Purification
of elements present in minute quantities
...
2 – 0
...
2
...
4
...
Properties
(i) It can be hardened by
heat treatment
Uses
(i) Lightly stressed machine
fittings, turbine, motors,
railway axels, crank
shafts, fish plates, cross
heads, etc
...
5 – 0
...
(ii) It can be welded with a
great care
Chrome Steel
1
...
Stainless steel
11
...
2% Ni
Resists corrosion
For making cutlery, utensils,
surgical instruments, automobile parts and cycle parts
...
It
selectively prevents ZnS from coming to the froth but allows Pbs to come with
the froth in froth floatation process
...
Name two metals which occur in native state in nature
...
Name the collector used in froth flotation process?
*3
...
4
...
Why can’t aluminium be reduced by carbon?
[Hint : Al is stronger reducing agent than carbon]
6
...
Mention its one use
...
: Cast iron is used for making gutter pipes, castings, railway sleepers,
toys etc
...
Name the impurities present in bauxite ore
...
What is the composition of copper matte?
9
...
What are froth stabilizers? Give two examples
...
A sample of galena is contaminated with zinc blend
...
12
...
: Cu = 25-30%, Zn = 25-30%, Ni = 40-50%]
13
...
: Sulphide ore particles are wetted by oil (pine oil) and gangue
particles by water]
**14
...
[Ans
...
Which method of purification is represented by the following reaction
Ti(s) + 2I2 (g)
16
...
Explain why?
[Hint : Zinc reacts at faster rate as compared with copper, further zinc is
cheaper than copper]
...
Write the composition of motlen mixture which is electrolysed to extract
aluminium
...
Differentiate between a mineral and an ore
...
Mention the role of graphite in the electrometallurgy of aluminium
...
Why is the froth floatation method selected for the concentration of sulphide
ores?
21
...
Name the method used for refining of germanium metal
...
Name two metals which are used for reduction in metallurgical process
...
The mixture of compounds A and B is passed through a column of Al2O3
by using alcohol as eluant
...
Which of the compounds A or B, is more readily adsorbed
on the column
...
What is hydrometallurgy? Give one example where it is used for metal
extraction
...
: Leaching followed by reduction is called hydrometallurgy
...
2
...
3
...
4
...
(b)
CaCO3 in the metallurgy of Fe
...
62
[Class XII : Chemistry]
5
...
Explain
...
: 2CuS(s) + C(s) CS2 (l) + 2Cu(s)
CuO(s) + C(s) CO (g) + Cu(s)
G value is more –ve in second case as compared with first case]
6
...
Why?
7
...
8
...
9
...
Why
does it contain such elements?
[Ans
...
They are not oxidised at anode
...
]
10
...
11
...
Why is the reduction of a metal oxide easier if metal formed is in liquid
state at the temperature of reduction?
[Hint : Entropy is higher when the metal is in liquid state as compared with
solid state, so G becomes more –ve]
13
...
[Ans
...
g
...
975 K
[ZnO + C Zn + CO]
14
...
15
...
Explain why?
Hint : E
16
...
How do we separate two sulphide ores by froth floatation method? Explain
with an example
...
How is copper extracted from low grade copper ore?
SA (II) TYPE QUESTIONS (3-Mark Questions)
1
...
(a)
Zone refining (b) Electrolytic refining (c) Vapour phase refining
...
How is pure copper obtained from its chief ore? Write the chemical reactions
occurring during the extraction
...
Name the method of refining of the following metals –
(a)
Hg
(b)
Sn
(c)
Cu
(d)
Ge
(e)
Ni
(f)
Zr
[Ans
...
The native silver forms a water soluble compound (B) with dilute aqueous
solution of NaCN in the presence of a gas (A)
...
Write the structures of (C) and (D) and identify (A) and (B) in
the following sequence –
Ag + NaCN + [A] + H2O [B] + OH– + Na+
...
[Ans
...
**5
...
Write a reaction used for the
preparation of wrought iron from cast iron
...
(a)
Name the metals which are associated with the following terms in
their extraction from their ores
...
CO in the extraction of nickel
Silica in the extraction of Cu
...
(c)
Silica is added to the sulphide ore of copper in the reverberatory
furnace
...
(e)
3
...
Vapour phase refining method is used for the purification of Ti
...
Is the reduction of Cr2O3 possible
with Al?
(b)
Describe how the following changes are brought about
...
Consequences
1
...
e
...
The other elements of the p-block have vacant d-orbitals in their
valence shell, e
...
elements of the third period have nine (9) valece orbitals
one 3s, three 3p and five three 3d orbitals
...
Following questions can be
answered:
(i)
(ii)
Sulphur (S) forms SF6 but oxygen does not form OF6
...
Why?
(iv)
(2)
Nitrogen (N) does not from pentahalide while P froms PCl5, PF5, and
–
PF6
...
Why?
The first member of p-block elements displays greater ability to from pp bond (s) with itself, (e
...
, C = C, C C, N = N, N N) and with the other
elements of second period, for example, C = O, C N, N = O compared
to the subsequent members of the group
...
Heavier members
can form p – d bonds with oxygen
...
66
[Class XII : Chemistry]
SiH3
Now, the following questions can be explained using the above mentioned
reasoning :
(i)
(ii)
Oxygen exists as O2 but sulphur as S8
...
Nitrogen forms N 2 but phosphorus forms P 4 at room
temperature
...
Due to small size and high electronegativity and presence of lone pair(s)
of electrons, elements N, O, F when bonded to hydrogen atom, forms
hydrogen bonds which are stronger than other intermolcular forces
...
p
...
p
...
Isostructural species have same number of bond pairs and lone pairs if present
around the central atom in a molecule/ion
...
For example,
–
ICl4 / XeF4, BrO3–/XeO3, BH4–/NH4+ are the pairs of isostructural species
...
This increased nuclear
charge holds the ns2 electrons of heavier elements strongly and the tendency of
ns2 electrons to take part in bonding is more and more restricted down the
group
...
Following questions can be explained with the help of inert
pair effect
...
Explain why?
(b) NaBiO3 is a strong oxidising agent
...
(c)
In group 16, stability of + 6 oxidiation state decreases and the stability
of + 4 oxidation increases down the group
...
Explain why?
(e) Why is BrO– a stronger oxidising agent than ClO– ?
4
4
[Hint : It is because + 7 oxidation state in less stable in BrO4– due
to which Br – O bond becomes weaker
...
[Hint : More effective nuclear charge in As than Sb
...
The two oxygen–oxygen
bond lengths are identical in the O3 molecule because it is resonance hybrid of
following two cannonical forms
...
This is because the third N–OH bond is not involved
in resonance
...
(i)
In SO2, the two sulphur-oxygen bonds are identical
...
Why?
Bond angle : In regular structures (where no lone pairs are present in the
valence shell of the central atom in a molecule/ion), the bond angle does not
68
[Class XII : Chemistry]
depend upon the size/electronegativity of the central or terminal atoms
...
+
N
109
...
This results in more bond pair-bond pair repulsion in NH3
molecule than PH3 molecule
...
Now the following questions can be explained using the above mentioned concept
...
Why?
(ii)
H–O–H bond in H2O in greater than H–S–H angle in H2S
...
More the molar mass, the higher is the m
...
and b
...
Hydrides
forming intermolecular hydrogen bonds have exceptionally high m
...
and b
...
since intermolecular hydrogen bonds are stronger than the van der Waals forces
...
(ii)
H2O is liquid and H2S is gas or H2S is more volatile than H2O
...
Due to the increase in size down the group, bond dissociation
enthalpy of E - H bond decreases
...
The following questions can be explained using the above concepts
...
(ii)
Among hydrogen halides, HI is the strongest reducing agent
...
(iv)
NH3 is mild reducing agent while BiH3 is the strongest reducing agent
among the group-15 hydrides
...
Basic nature of hydrides EH3 of group 15 elements
All the hydrides EH3 of group 15 elements has one lone pair of electrons
...
The sp3 hybrid orbital is directional and further N is more electronegtive than H,
the bond pair of N - H is shifted towards N atom which further increases the
electron density on N atom
...
As a result PH3 is less basic
than NH3 and basic character decreases down the group
...
(SiH3)3N has less Lewis basic nature than that of
(CH3)3N because lone pair of electrons in p - orbital of N atom in (SiH3)3N is
transferred to the vacant d - orbital of Si atom forming d – p fond
...
Compounds
having more ionic character have more m
...
and b
...
than the compounds having
more covalent character
...
Explain why :
(i)
SnCl2 has more b
...
than SnCl4
...
(iii)
PCl5 has lower boiling point than that of PCl3
...
Strength of oxoacids increases if the number of oxygen atoms bonded with E
increases
...
The more the electrongeativeity, stronger is the
oxoacid
...
This is because the stabilisation of the oxoanion
increases with the number of the oxygen atoms bonded to the halogen atom
...
Oxidising Power of Halogens :
eg
–hyd H
The more negative the value of rH =
1
H – eg H – hyd H, the higher
2 diss
will be oxidising property of the halogen and more positive will be standard
reduction potential Ered of the halogen
...
(i)
Why does F2 have exceptionally low bond dissociation enthaply?
(ii)
Although electron gain entharpy of fluorine(F) is less negative as compared
to chlorine (Cl), Flunorine gas (F2) is a stronger oxidising agent than Cl2
gas
...
In group 15 elements, there is considerable increase in covalent radius
from N to P but small increase from As to Bi
...
2
...
Explain
...
3
...
Why?
4
...
Assign a reason
...
]
5
...
Explain why?
6
...
Why?
7
...
Why?
[Hint : Due to the presence of odd electron on N in NO2]
8
...
9
...
10
...
Write disproportionation reaction of H3PO3?
12
...
[Hint : Ammonia acts as a Lewis base therefore, it can donate a pair of
electrons to central metal atom or ion
...
Write the reaction of PCl5 with heavy water
...
73
[Class XII : Chemistry]
14
...
” Justify with an example
...
15
...
Why is Bi(V) a stronger oxidant than Sb(V)?
[Hint : +3 oxidation state is more stable than +5 oxidation state in Bi]
...
How many P – O – P bonds are there in cyclotrimetaphosphoric acid?
18
...
19
...
20
...
21
...
SA (I) TYPE QUESTIONS (2-Mark Questions)
Complete the following reactions :
1
...
NH4Cl (aq) + NaNO2 (aq)
(ii)
3
...
(i)
I2 + HNO3 (conc
...
PCl3 + 3H2O
PCl5 + H2O
(i)
NO3– + Fe2+ + H+
Zn + HNO3 (dil)
(i)
Zn + HNO3 (conc)
P4 + HNO3 (conc)
(i)
NH3 + O2
500K, 9 bar
P4 + NaOH + H2O
(i)
NH3 (Excess) + Cl2
NH3 + Cl2 (Excess)
(i)
P4 + HNO3 (conc
...
(i)
(ii)
10
...
HgCl2 + PH3
(ii)
8
...
PH4I + KOH
(ii)
6
...
4H3PO3
Cu + HNO3 (conc
...
Give chemical reaction in support of the statement that all the bonds in
PCl5 molecule are not equivalent
...
Arrange the following trichlorides in decreasing order of bond angle :
NCl3, PCl3, AsCl3, SbCl3
15
...
Assign the
reason :
PH3, NH3, SbH3, AsH3, BiH3
...
Write the conditions that favour the formation of ammonia gas along with
the reactions involved in Haber’s Process
...
(i)
What is the covalency of N in N2O5?
(ii)
Explain why phosphorus forms pentachloride whereas nitrogen and
bismuth do not?
(i)
The acidic character of hydrides of group 15 increases from NH3 to
BiH3, Why?
(ii)
Phosphorus show marked tendency for catenation
...
19
...
Which one
of these two types of phosphorus is more reactive and why?
20
...
Give any two
uses of HNO3
...
How is ammonia manufactured industrially? Draw flow chart for the
manufacture of ammonia
...
How is HNO3 prepared commercially?
(ii)
Write chemical equations of the reactions involved
...
(i)
What concentration by mass of HNO3 can be obtained?
An unknown salt X reacts with hot conc
...
On adding dilute
ferrous sulphate solution to an aqueous solution of X and then carefully
adding conc
...
Identify X and
Y and write the chemical equation involved in the reaction
...
76
[Class XII : Chemistry]
3
...
Allotrope (A) on reaction with very dilute
aqueous NaOH liberates a highly poisonous gas (C) having a rotten fish
smell
...
Identify the compounds (A) to (E)
...
Assign the appropriate reason for the following:
(a)
Nitrogen exists as diatomic molecule and phorphorous as P4 at room
temperature
...
(c)
Why is N2 unreactive at room temperature?
[Hint :
(a)
(b)
5
...
whereas P does not form p – p bonds but
forms P – P single bond
...
Write balanced equation for the following reactions :
(a)
(b)
copper metal with conc
...
(c)
6
...
Iodine is treated with conc
...
Explain each of the following :
(a)
–
The bond angles (O–N–O) are not of the same value in NO2
and NO2
...
(c)
Ammonia has greater affinity for protons than phosphine
...
Explain, why SF4 is easily hydrolysed, whereas SF6 is resistant to hydrolysis?
[
Hint
: Water molecule can not attack ‘S‘ atom due to steric hinderance
and ‘S’ atom is also coordinately saturated in SF6 molecule
...
In group 16, the stability of +6 oxidation state decreases and that of +4
oxidation state increases down the group
...
Draw the structure of H2S2O8 and find the number of S–S bond if any
...
Which one of the following is not oxidised by O3
...
Kl, FeSO4, K2MnO4, KMnO4
[Hint
...
]
5
...
Why?
6
...
Why?
7
...
8
...
Explain
why?
9
...
Ka2 << Ka1 for H2SO4 in water, why?
11
...
12
...
Give reason
...
H2O is a liquid while inspite of a higher molecular mass, H2S is a gas
...
14
...
O3 acts as a powerful oxidising agent
...
All the bonds in SF4 are not equivalent
...
What happens when sulphur dioxide gas is passed through an aqueous
solution of a Fe(III) salt?
78
[Class XII : Chemistry]
SA(I) TYPE QUESTIONS (2-Mark Questions)
1
...
Glucose in heated with conc
...
Sodium nitrate is heated with conc
...
Complete the following reactions :
(i)
(ii)
4
...
PbS + O3
S8 + H2SO4 (conc
...
(i)
SF6 is inert and stable but SF4 is reactive
...
H2S is more acidic than H2O
...
6
...
Explain why O3 is thermodynamically less stable than O2?
8
...
H2SO5
SO32–
Mention the favourable conditions for the manufacture of sulphuric acid by
contact process
...
(i)
How does O3 react with lead sulphide? Write chemical equation
...
Explain why?
79
[Class XII : Chemistry]
2
...
(ii)
H2O is less acidic than H2Te
...
3
...
4
...
2
...
)
3
...
CaF2 + H2SO4 (conc
...
The gas is also produced as a by-product during roasting of
sulphide ore
...
KMnO4 solution
...
[Hint : A = S8;
6
...
? Write balanced equation
...
GROUP 17 ELEMENTS
VSA QUESTIONS (1-Mark Questions)
1
...
[Hint : because of unavailability of d orbitals in its valence shell
...
Why HF is the weakest acid and HI is the strongest
...
3
...
[Hint : High electronegativity and more negative eletron gain enthalpies of
halogens]
80
[Class XII : Chemistry]
4
...
Bond dissociation enthalpy of F2 is less than that of Cl2
...
What is cause of bleaching action of chlorine water? Explain it with chemical
equation?
[Hint : Formation of nascent oxygen]
7
...
[Hint
...
So the incoming electron does experience mere repulsion in F
than in Cl]
...
Why can’t we prepare HBr by heating KBr with sulphuric acid
...
Fluorine exhibit only –I oxidation state whereas other halogens exhibit +ve
oxidation states also
...
Arrange the following oxoacids of chlorine in increasing order of acid strength:
HOCl, HOClO, HOClO3, HOClO3
11
...
12
...
13
...
14
...
Explain
...
Why does fluorine not play the role of a central atom in interhalogen
compounds?
16
...
Explain
...
Interhalogen compounds are more reactive than halogens except F2
...
(i)
Give one important use of ClF3
...
(ii)
What happens when NaCl is heated with conc
...
Write the chemical equation
...
A colourless pungent smelling gas, which easily liquifies to a colourless
liquid and freezes to a white crystalline solid, gives dense white fumes with
ammonia
...
[Hint : HCl]
4
...
[Hint : U(s) + 3ClF3(l) UF6(g) + 3ClF(g)
5
...
Complete the following reqctions
...
N2 (Excess) + Cl2
(i)
Na2SO3 + Cl2 + H2O
N2 + Cl2 (Excess)
(i)
Cl2 + NaOH (cold and dil)
Cl2 + NaOH (hot & conc)
(i)
Fe + HCl
(ii)
11
...
(i)
(ii)
9
...
Al2O3(s) + NaOH (aq) + H2O(l)
(ii)
7
...
Give appropriate reason for each of the following :
(i)
Metal fluorides are more ionic than metal chlorides
...
*(iii) Addition of chlorine to KI solution gives it a brown colour but excess
of Cl2 makes it colourless
...
(ii)
–
ClO4 is more resonance stabilised than SO42– since dispersal of
–
negative charnge is more effective in ClO4 as compared with SO42–
(iii)
2KI + Cl2 2KCl + I2
5Cl2 (Excess) + I2 + 6H2O 2HIO3 + 10 HCl
(Colourless)
2
...
It partially dissolves in H2O to give a solution which turns blue
litmus red
...
(a)
(b)
What are the products obtained when X2 reacts with H2O? Write
chemical equation
...
Identify X2, name the group to which it belongs
...
NaOH? Give
equation
...
(b)
HF, HCl, HBr, HI (decreasing acid strength)
...
[Hint :
(a)
F2 has exceptionally low bond dissociation enthalpy
...
Stronger
2
electron–electron repulsions among the lone pairs in F2 molecule
make its bond dissociation enthalpy exceptionally low
...
Acid strength depends upon H–X bond dissociation enthalpy
...
Electron availability on the central atom ‘E’ in EH3 decreases down
the group
...
What inspired N
...
Predict the shape and the asked angle (90º or mre or less) in the
following case:
XeF2 and the angle F–Xe–F
3
...
Why do some noble gases form compounds with fluorine and oxygen only?
5
...
Why?
6
...
Why?
7
...
8
...
Suggest reason why only known binary compounds of noble gases are
fluorides and oxides of Xenon and to a lesser extent of Kryton
...
Kr and Xe both have
low lonisation enthalpies as compared to He and Ne
...
(a)
Hydrolysis of XeF6 is not regarded as a redox reaction
...
84
[Class XII : Chemistry]
[Hint : (b) XeF4 + 2H2 Xe + 4HF)]
3
...
XeF2 is hydrolysed
PtF6 and Xenon are mixed together
...
Draw the structures of BrF3, XeOF4, XeO3 using VSEPR theory
...
Account for the following :
(a)
(b)
7
...
The majority of known noble gas compounds are those of Xenon
...
Assign reason to the following :
(i)
(ii)
No chemical compound of helium is known
...
(ii)
3
...
(iii)
2
...
Draw the structure of XeF4
...
XeOF4
(ii)
XeF6
(iii) XeO3
85
[Class XII : Chemistry]
Complete the reactions :
(i)
XeF2 + NaF
(ii)
(iii)
5
...
Ramesh (a chemical engineer by profession) and his friends want to get
up a paper plant to produce nearly 100 TPD white paper of various types
...
Either to use cheap and easily
available chlorine or to use more expensive ozone
...
(a)
Write an equation for the manufacture of ozonised oxygen from
oxygen
...
(b)
Why ozone is considered to be a better bleaching agent than chlorine
...
LONG ANSWER TYPE QUESTIONS (5-Mark Questions)
1
...
2
...
[Hint : A is P4]
...
A white waxy translucent solid, M, insoluble in water but soluble in CS2
glows in dark
...
Also M catches fire to give dense white fumes of Q :
(a)
(b)
‘M’ exists in the form of discrete tetrahedral molecules
...
(c)
4
...
‘M’ on heating at 573 K is changed into other less reactive form,
Q, which is non-poisonous, insoluble in water as well as in CS2 and
does not glow in dark, Identify Q and draw its structure
...
[Hint
...
5
...
(b)
H2O is less acidic than H2S
...
(d)
H3PO2 and H3PO3 act as reducing agents while H3PO4 does not
...
87
[Class XII : Chemistry]
6
...
(b)
Deduce the structure of XeF6 using VSEPR theory
...
(e)
7
...
(a)
Why does nitrogen show anomalous behaviour? Discuss the trend
of chemical reactivity of group 15 elements with
...
oxygen
(b)
halogens
(c)
metals
H3PO3 is a dibasic acid
...
(b)
Ammonia is a good complexing agent
...
(d)
PCl5 is ionic in solid state
...
88
[Class XII : Chemistry]
Unit - 8
d–and f–BLOCK ELEMENTS
Electronic Configuration of Transition Metals/Ions
The d-block element is called transition metal if it has partly filled
d-orbitals in the ground state as well as in its oxidised state
...
Exceptions in electronic configuration are due to (a) very little engery difference
between (n–1) d and ns orbitals and (b) extra stability of half filled and completely
f led orbi al i case of C r and C u in 3d series
...
For
example, the outer electronic configuration of Cu + , Cu 2+ and Cr 3+ are
respectively 3d10, 3d9 and 3d3
...
(i)
Scandium (Z = 21) is a transition element but zinc (Z = 30) is not
...
e
...
why are these elements regarded as transition
elements?
(iii)
Which of the d-block elements are not regarded as transition
elements?
Understanding fus H vap H and a H
In transition metals unpaired (n - l)d electrons as well as ns electrons take
part in interatomic bonding
...
fusH
M(s) M(l)
H
vap
M(l) M(vapour)
89
[Class XII : Chemistry]
aH
M(s) M(g)
These enthalpies are related as
fus H < vap H < a H
The following questions can be explained using the above reasoning
...
p
...
p
...
Metals of second (4d) and third (5d) transition series have greater
enthalpies of atomisation than corresponding elements of first transition series
on account of more frequent metal metal bonding due to greater spatial
extension of 4d and 5d orbitals than 3d orbitals
...
The filling of 4f orbitals before 5d orbitals results in the
gradual increase in effective nuclear charge resulting in a regular decrease in
atomic and ionic radii
...
The
corresponding members of second and third transition series have similar radii
because the normal size increase down the group of d-block elements almost
exactly balanced by the lanthanoid contraction
...
(i)
Elements in the’following pairs have identical (similar) radii : Zr/Hf, Nb/Ta
and Mo/W
...
There are some irregular
variations
...
Second ionization enthalpy of Zn (i H2 = 1734 kJ/mol) is lower than
second ionization enthalpy of Cu (1958 kJ/mol)
...
Cr = 3d5 4s1
Zn = 3d10 4s2; Zn2+ = 3d10
Cu = 3d10 4s1; Cu2+ = 3d9
Now the following questions can be accounted for :
(i)
Why is second ionization enthalphy of Cr (z = 24) more than that
+
Mn (z = 25) (Hint
...
(ii)
Which has more second ionisation enthalpy Cu (z = 29) or
Zn (z = 30)?
(Hint
...
[iii)
Second ionization enthalpy of Mn (z = 25) is less than that of Fe(z = 26)
but third ionisation enthalpy of Mn is more than that of Fe
...
Transition metals show variable oxidation states due to incompletely filled
d-orbitals
...
g
...
Scandium is the only
transition element which exclusively shows the oxidation state of +3
...
S
...
S
...
This makes r G less than zero for all 3d-elements except Cu
for which r G is positive which shows that Cu(s) Cu2+ + 2e– is nonspontaneous
...
This
makes r G positive for Cu only
...
r G n EM/M2 F n E M2 /M F nE M2 /M or
F
EM2 /M
rG
nF
Since the sum of i H1 and i H2 generally increases with the increase in
the atomic number of the transition metal, therefore E M 2+ M value becomes less
and less negative
...
This
is because i H2 for Mn and Zn produces stable d5 configuration (Mn2+) and d10
configuration (Zn2+) are produced and therefore requirement of energy is less
...
Example : Why is E value for Mn3+ / Mn2+ couple much more positive than
for Cr3+ / Cr2+ or Fe3+ / Fe2+
...
Cr2+ (d4) Cr3+ (d3)
Cr3+ has half-filled t 2g level
...
Hence E value is compartively less
...
Example : Which is stronger reducing agent Cr 2+ or Fe2+ and why?
3
Solution : Cr2+ (d4) Cr3+ (d3 or half-filled t 2g
92
[Class XII : Chemistry]
In water medium [Cr (H2O)6]3+ has more CFSE than [Fe (H2O)6]3+
...
Stability of Higher Oxidation States
Higher oxidation states are shown by transition metals in fluorides, oxides,
oxocations and oxoanions
...
g
...
Transition metals show highest oxidation state in oxides and oxocations
+
and oxoanions, e
...
, VO4 and VO4–
...
The following questions can be explained using the above concepts :
(i)
All Cu (II) halides are known except the iodides
...
(iv)
E values of 3d series varies irregularly
...
For example, they display a variety of oxidtion states, form coloured
ions and enter into complexe formation
...
93
[Class XII : Chemistry]
Crystal Field Theory
Calculation of CFSE : Each electron occupying t2g orbital results in the lowering
of energy by 0
...
60 0
...
of electrons occupying t2g orbitals and ‘y’ is
the no
...
60 0y –0
...
For example, in the
octahedral crystal field of ligands, the d-orbitals are split into two sets of dorbitals (i) t2g orbitals of lower energy : these are dxy dyz, dxz and (ii) eg orbitals
of higher energy : these are dx2–y2 and dz2
...
During this d-d transition, a
characteristic wave length of visible light is absorbed and therefore transmitted
light appears coloured
...
94
[Class XII : Chemistry]
No d-d transition occurs if d-orbitals are empty or fully filled and therefore, such
ions may be colourless
...
During this process, characteristic wave length of visible
light is absorbed
...
Comparision of oxidising powers of KMnO4 and K2Cr2O7
MnO2– + 2H2O + 3e– Mn2 + 4OH–
E = + 1
...
52 V
Cr2O72– + 14H+ + 6e– 2Cr3+ + 7H2O
E = + 1
...
But KMnO4 in faint alkaline medium is
a stronger oxidising agent than acidified KMnO 4
...
(b)
Overall :
Mn2+ + 4H2O] 2
I2 + 2e–] 2
2Mn4– + 10 I– + 16 H+
2Mn2+ + 8H2O + 5I2
MnO4– + 2H2O + 3e–
MnO2 + 4OH–] 2
I– + 6 OH–
Overall :
MnO4– + 8H+ + 5e–
2I–
(a)
IO3– + 3H2O + 6e–
2MnO4– + H2O + I–
2MnO2 + IO3– + 2OH–
95
[Class XII : Chemistry]
Following reactions involving the oxidising action of KMnO4 and K2Cr2O7
may be written in the above shown manner :
(i)
How do acidified KMnO4 and acidified K2Cr2O7 reacts separately with (a)
SO2, (b) H2S (c) FeSO 4 (d) S2O3– in alkaline medium?
(ii)
Write the ionic equations of acidified KMnO4 with (a) oxalate ion (b) Mohr
salt (c) NO2– and (d) Iron (II) oxalate (e) Mn 2+ in alkaline medium?
[Hint : (d) Both Fe2+ and C2O42– are oxidised to Fe3+ and CO2 respectively
...
They
also show oxidation states of +2, and +4 if the corresponding lanthanoid ions
have extra stable 4f 0, 4f7 and 4f14 configuration
...
S
...
S
...
Eu2+ Eu3+ + e–, +3 more stable O
...
than +2
Yb2+ Yb3+ + e–, + 3 more stable O
...
than + 2
Hence, both Eu2+ and Yb2+ act as strong reducing agents
...
S
...
Actinoids also show higher oxidation states, e
...
, Th (+4), Pa
(+5), U (+ 6) and Np (+ 7)
...
Why?
Solution : La3+, Gd3+ and Lu3+ have stable configurations 4f0, 4f7 and 4f14
respectively
...
S
...
5f orbitals in actinoids are not as burried as 4f orbials in lanthanoids and hence
5f electrons can participate in bonding to a far greater extent
...
Since 5f orbitals are larger and more diffuse than 4f orbitals, their
penetration towards the inner core of electrons is less than the penetration of
4f elecrons
...
Consequently, effective nuclear charge in actinoids
increases at faster rate as compared with lanthanoids
...
VERY SHORT ANSWER TYPE QUESTIONS (1 - Mark Questions)
1
...
Explain CuSO4
...
Why is the third ionisation energy of manganese (Z = 25) is unexpectedly
high?
[Hint : The third electron is to be removed from stable configuration of
Mn2+ (3d5)
...
]
4
...
Silver (Ag) has completely filled d-orbitals (4d10) in its ground state
...
[Hint : Ag2+ (d9)]
6
...
Why?
[Hint : Poor interatomic bonding in zinc due to all paired electrons in 3d
subshell]
7
...
8
...
Why?
9
...
10
...
why?
[Hint : Increasing value of effective nuclear charge due to lanthanoid
contraction
...
Why Mn2+ compounds are more stable than Fe2+ compounds towards
oxidation to their +3 state?
12
...
[Hint : µ =
n (n + 2) B
...
]
13
...
14
...
What are interstitial compounds?
16
...
Give two specific reasons to justify the statement
...
Write the chemical equation for the reaction of thiosulphate ions and alkaline
potassium permanganate
...
Mention the name and formula of the ore from which potassium dichromate
is prepared
...
19
...
Write the names of the catalysts used in the :
(a)
Manufacture of sulphuric acid by contact process
...
21
...
22
...
23
...
Draw the structure of dichromate anion
...
Arrange the following monoxides of transition metals on the basis of
decreasing basic character TiO, VO, CrO, FeO
...
Why is Cr2+ reducing and Mn 3+ oxidising when both have d4 configuration?
[Hint :
Cr2+ (d4) Cr3+ (t32g) + e–
Mn3+ (d4) + e– Mn2+ (3d5)
This is because extra stability is associated with half-filled t2g level and
half-filled d5 configuration
...
How would you explain more odixising power of MnO4– than Cr2O72–?
[Hint :
MnO4– Mn2+ (3d5)
Cr2O72– + 6e– 2Cr3 + (t32g)
Stability of Mn2+ is more than that of Cr3+]
28
...
Why MnO4– or Cr2O72– is intensely coloured?
[Hint : Mn7+(3d°) and Cr6+ (3d°) are intensely coloured because electronic
transition i
...
, charge transfer from O2– ions Mn7+ in MnO4– or to Cr6+ in
Cr2O72– occurs upon the absorption of visible light radiations and therefore
these oxoanions exhibit colour which is complementry to the colour absorbed
by these ions
...
Transition metals show low oxidation stales like 0, –1, –2 etc with-acceptor
ligands like CO
...
]
99
[Class XII : Chemistry]
SHORT ANSWER TYPE QUESTIONS (2-Mark Questions)
1
...
2
...
Why?
3
...
K2Cr2O7 from (i) Chromite ore and (ii) Cr2O3
KMnO4 from Pyrolusite ore (MnO2)
...
In permanganate ions, all bonds formed between manganese and
oxygen are covalent
...
Write complete chemical equations for :
(a)
(b)
oxidation of Mn2+ by MnO4– in neutral or faintly alkaline medium
...
oxidation of Fe2+ by Cr2O72– in acidic medium
Out of Fe and Cu, which one would exhibit higher melting point?
[Hint
...
(ii) Fe has higher melting point due to presence of more unpaired electrons
3d-orbitals
...
Describe giving reason which one of the following pairs has the property
indicated :
(a)
(b)
8
...
Co2+ or Ni2+ (lower magnetic moments)
...
Complete the following equations :
(a)
MnO2 + KOH + O2
100
(b)
Na2Cr2O7 + KCl
[Class XII : Chemistry]
10
...
[Hint : CO is a acceptor ligand capable of forming a bond by accepting
electrons from the filled d-orbitals of transition metal and CO also form
bond by donating its electrons to transition metal orbital
...
For the first row transition metals the enthalpy of atomisation value are :
Sc
aH/kJ mol–1
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
326
473
515
397
281
416
425
430
339
26
Assign reason for the following :
(a)
(b)
12
...
The enthalpy of atomisation of zinc is the lowest in 3d - series
...
(b)
Scandium (Z = 21) does not exhibit variable oxidation states
...
Copper (I) compounds undergo disproportionation
...
14
...
MnO4– + NO2– + H+
513 K
KMnO4
The following two reactions of HNO3 with Zn are given
...
HNO3 Zn(NO3)2 + X + H2O
(b)
Zn + dil
...
[Hint : X is NO2 and Y is N2O]
...
For M2+/M and M3+/M2+ systems the E values for some metals are
as follows:
Cr2+/Cr
–0
...
2V
Mn3+/Mn2+
1
...
4V
Fe3+/Fe2+
0
...
04V
[Class XII : Chemistry]
Use this data for comment upon :
(i)
the stability of Fe3+ in acid solution to that of Cr3+ or Mn+3/
(ii)
the ease with which iron can be oxidised as compared to a similar
process for either Cr or Mn metal
...
For the first row transition metals, the E values are :
E
V
(M+2/M) –1
...
91
–1
...
44
–0
...
25
+0
...
[Hint : Due to irregular variation of iH1 + iH2 and their sublimation
enthalpies, aH]
18
...
73 BM in its compound
...
N
...
19
...
Transition metals and majority of their compounds act as good
catalysts
...
[Hint : 3, 5, 4, 1]
21
...
[Hint : 2/5 moles]
...
Account for the following :
(a)
(b)
Zn2+ salts are white
...
La(OH)3 is more basic than Lu(OH)3
Cu(I) compounds are unstable in aqueous solution and undergo
disproportination
...
Write ionic equations for its reaction (acidic medium) with
...
Why do transition metals form alloys?
(c)
*4
...
Iodide ion
(b) Iron (II)
(c) H2S
...
In the following reaction, Mn(VI) changes to Mn(VII) and Mn(IV) in acidic
solution
...
Explain why Mn(VI) changes to Mn(VII) and Mn(IV)
...
(b)
ferrous oxalate reacts with acidified KMnO4
...
*6
...
Ti4+ = 3d0
no
...
of unpaired e– = 2
µ = 2
...
of unpaired e– = 4
µ = 4
...
Complete and balance the following equations
(a)
(b)
Heat
KMnO4
(c)
8
...
H+ + MnO4– + Fe2+ + C2O42–
How do you account for the following?
(a)
With the same d-orbital configuration (d4), Cr2+ is a reducing agent
while Mn3+ is an oxidiising agent
...
(c)
Most of transition metal ions exhibit characteristic colours in aqueous
solutions
...
A green compound ‘A’ on fusion with NaOH in presence of air forms yellow
compound ‘B’ which on acidification, gives orange solution of compound
‘C’
...
Identify compounds A to D and write the chemical equation of the
reactions involved
...
Assign reasons for the following :
(a)
(b)
There is gradual decrease in the ionic radii of M2+ ion in 3d-series
...
(d)
Ce3+ can be easily oxidised to Ce4+
(e)
3
...
Tantalum and palladium metals are used to electroplate coinage
metals
...
(b)
Yb2+ behaves as a good reductant
...
104
[Class XII : Chemistry]
(d)
(e)
*4
...
Hydrochloric acid attacks all the actinoids
...
(c)
AgCl dissolves in ammonia solution
(d)
Out of Cr2+ or Fe2+, which one is a stronger reducing agent?
(e)
**5
...
The highest oxidation state is exhibited in oxoanions of a transition
metal
...
H2SO4, a reddish brown gas B is evolved, which gives a yellow coloured
solution C when passed through NaOH
...
D is obtained
...
Identify A, B, C, D and E and write the chemical equations for the reactions
involved
...
(C) Na2CrO4
I
H
Describe the preparation of potassium dichromate (K2Cr2O7)
...
(b)
7
...
” Why? Give chemical equations in favour of your
answer
...
(b)
E 2+ Cu has positive value but other 3d-elements have negative value
...
Elements in the middle of transition series have higher melting points
...
(a)
Compare the chemistry of the actinoids with that of lanthanoids with
reference to :
(i)
(ii)
oxidation states
(iii)
(b)
electronic configuration
chemical reactivity
...
of the d4 species, Cr2+ is strongly reducing while Mn3+ is strongly
oxidising
...
(a)
What is meant by disproportionation of an oxidation state
...
(b)
Explain why europium (II) is more stable than Ce(II)?
[Hint : (a) When particular state becomes less stable relative to
other oxidation states, one lower and one higher, it is said to undergo
disproportionation, for example,
(b)
Eu (II) : [Xe] 4f7 5d0 (4f subshell is half-filled)
Ce (II) : [Xe] 4f1 5d0 (5d subshell is empty and 4f subshell has only
one electron which can be easily lost
...
(a)
A blackish brown coloured solid ‘A’ when fused with alkali metal
hydroxide in presence of air, produces a dark green coloured
compound ‘B’, which on electrolytic oxidation in alkaline medium
gives a dark purple coloured compound C
...
(b)
What happens when an acidic solution of the green compound (B)
is allowed to stand for some time? Give the equation involved
...
A mixed oxide of iron and chromium FeO
...
On acidification the compound (A) forms an orange coloured compound
(B), which is a strong oxidizing agent
...
(ii)
Write balanced chemical equation for each step
...
**12
...
Compound (B) disproportionates in neutral or acidic solution
to give purple compound (C)
...
Identify compounds A to D and also explain the reactions involved
...
B = K2MnO4
C = KMnO4
D =KIO3
Give reasons for the following :
(i)
Fe has higher melting point than Cu
...
(iii)
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless
...
(v)
Transition metals sometimes exhibit very low oxidation state such
as +I
...
A violet compound of manganese (A) decomposes on heating to liberate
oxygen and compounds (B) and (C) of manganese are formed
...
On heating compound (C) with conc
...
Identify compounds A to D and also explain the reactions involved
...
One day a salesman selling cutlery knocked at the door of Rita
...
The salesman showed Rita some cutlery made of German
silver
...
In the mean time Rita’s next door friend Manju arrived
...
Manju is a science graduate
...
(a)
Explain why Manju stopped Rita from buying the cutlery?
(b)
Write the composition of German Silver
...
(d)
What values are exhibited by Manju?
108
[Class XII : Chemistry]
Unit - 9
COORDINATION COMPOUNDS
Points to Remember
•
Coordination compounds as well as double salts are formed by the
combination of two or more stable compounds combined in stoichiometric
ratio
...
(NH4)2
...
K4[Fe(CN)6] 4K+ + [Fe(CN)6]4–
•
Coordination entity is composed of central atom to which ligands are
bound
...
•
Coordination number is number of sigma bonds formed between ligands
and the central atom
...
•
Oxidation number of a central atom in a coordination entity is defined
as the charge it would bear if all ligands were removed along with the
electron pairs that were denoted by the ligands to the central atom and
it is represented by a roman numeral
...
Examples are
NO2– and SCN–
O
M
N
or M
O
N
or
O
NCS
O
M
SCN
M
•
Tetrahedral complexes of the type [MX2L2] type do not show gemetrical
isomerism
...
109
[Class XII : Chemistry]
•
•
•
•
•
•
•
•
•
•
•
•
Square planar complex of the type MABXL where A, B, X, L are unidentate
ligands, shows three geometrical isomers : two cis and one trans
...
Octahedral complexes of type [M (AA)2 B2], [M (AA)2 AB] show both
geomerical and optical isomerism
...
e
...
Octahedral complexes of the type [M (AA)3] show optical isomerism
...
Valence Bond theory can predict the geometry of a coordination entity if
and only if its magnetic behaviour is known
...
e
...
e
...
According to VBT if coordination number is 4, complex may be tetrahedral
(sp3) or square planar (dsp 2)
...
Crystal field splitting is observed due to the lose of degenracy of d-orbitals
in the tetrahedral and octahedral fields produced by the ligands
...
(i)
geometry of coordination entity (ii) charge on the metal ion
(iii) field produced by the ligants
...
Strong ligands are those which are bound to the central atom through
either C or N and produce strong field
...
The colour of complex ion depends upon the nature of ligand and may
be due to d-d transition upon the absorption of characteristic radiations
of visible light
...
K n
•
The metal-carbon bond in metal carbonyls possesses both and
character
...
This
unique synergic bonding provides stability to metal carbonyls
...
Define the term ‘coordination compound’
...
Write the oxidation state of nickel in [Ni(CO)4]
...
What is the coordination number of central atom in [Co(C2O4)3]3– ?
4
...
Write the IUPAC name of [Pt
...
6
...
Give IUPAC name of ionisation isomer of [Ni(NH3)3[NO3]Cl
...
Write down the formula of tetramineaquachloride Coalt (III) chloride
...
Write the IUPAC name of [Cr(NH3)6][Co(CN)6]
...
Write the IUPAC name of [Pt Cl2(en)2](NO3)2
...
Write IUPAC name of linkage isomer of [Cr(H2O)5(SCN)]2+
...
Arrange the following in the increasing order of conductivity in solution
...
How many geometrical isomers are possible for the tetrahedral complex
[Ni(CO)4]
...
: No isomer, as the relative positions of the unidentate ligands attached
to the central metal atom are always the same with respect to each other]
...
Write the formula and the name of the coordinate isomer of [Co(en)3]
[Cr(CN)6]
...
Give an example of coordination isomerism
...
What is ambidentate ligand? Give an example
...
Indicate the types of structural isomerism exhibited by the complex
[Co(NH3)5(NO2)](NO3)2
...
Arrange the following ligands in increasing order of o (Crystal field splitting
energy) for octahedral complexes with a particular metal ion
...
111
[Class XII : Chemistry]
19
...
Given that overall stability constant (4) for this complex is 2
...
[Ans
...
7 × 10–14]
20
...
21
...
[Ans
...
Name the compound used to estimate the hardness of water volumetrically
...
Name one homogeneous catalyst used in hydrogenation of alkenes
...
Give two names of coordination complexes which are used in medicines
...
Why is CO a stronger ligand than Cl– ?
SA(I) TYPE QUESTIONS (2-Mark Questions)
26
...
27
...
28
...
29
...
(a)
[Co(NH3)4(H2O)Cl]Cl 2
(b)
[CrCl2(en)2]Cl; [en=ethane–1,2–diamine]
**30
...
Co3+ ion is bound to one Cl–, one NH3 molecule and two bidentate
ethylene diamine (en) molecules
...
Write
the name and magnetic behaviour of each of the above coordination
entities
...
Terabromidocuprate (II)
Pentaamminenitrito–O–Cobalt (III)
What type of structural isomerism is represented by the following complexes:
112
[Class XII : Chemistry]
(a)
[Mn(CO)5(SCN)] and [Mn(CO)5(NCS)]
(b)
[Co(NH3)5(NO3)] SO4
33
...
Calculate the magnetic moments of the following complexes :
(i)
35
...
(b)
NH3 acts as complexing agent but NH4+ does not
...
Explain on the basis of Valance Bond Theory that diamagnetic [Ni(CN)4]2–
has square planar structure and paramagnetic [NiCl4]2– ion has tetrahedal
geometry
...
Explain as to how the two complexes of nickel [Ni(CN)4]2– and Ni(CO)4
have different structures but do not differ in their magnetic behaviours
...
no
...
**38
...
0
...
372°C
...
86°C/m
[
Hint
: Tf = i Kf × m = i 1
...
1
Tf(obs) = 0
...
Hence the formula is [CO(NH3)4Cl2] Cl
39
...
Explain using Crystal Field Theory:
40
...
crystal field splitting in an octahedral field
spectrochemical series
What do you understand by stepwise stability constant and overall stability
constant of a coordination compound? How are these two constants related
to one another?
113
[Class XII : Chemistry]
42
...
[Ni(Co)4]
[Fe(Co)5]
How does EDTA help as a cure for lead poisoning?
[Ans
...
The
more soluble complex lead-EDTA is eliminated in urine]
...
How are complex compounds applicable in (a) electroplating of silver, gold
or other noble metals (b) photography
...
For the complex [Fe(en)2Cl2]Cl identify
(a)
(b)
the hybrid orbitals and the shape of the complex
...
(d)
the number of geometrical isomers
...
the oxidation number of iron
...
[At
...
of Fe = 26]
Draw the structure of
(a)
cis-dichloridotetracyanochromate (II)
(b)
mer-triamminetrichloridocobalt (III)
(c)
fac-triaquatrinitrito–N–cobalt (III)
*47
...
(iii)
48
...
[Co(NH3)6]3+ is an inner orbital complex whereas [Ni(MH3)6]2+ is in
outer orbital complex
...
(a)
[CoF6]3–
(c)
(b) [Cr(NH3)6]3+
[Fe(CN)6]4–
[Atomic Number : Co = 27, Cr = 24, Fe = 26]
114
[Class XII : Chemistry]
**49
...
The form ‘A’ reacts with AgNO3 solution to give white
precipitate which is readily soluble in dilute aqueous ammonia, whereas ‘B’
gives a pale yellow precipitate which is partly soluble in concentrated
ammonia solution
...
Also mention the
isomerism which arises among ‘A’ and ‘B’
...
50
...
Write the limitations of Valence Bond Theory
...
Draw a sketch to show the splitting of d-orbitals in an octahedral crystal
field state for a d4 ion
...
Describe with an example of each, the role of coordination compounds in
(i) biological system (ii) analaytical chemistry (iii) medicinal chemistry
...
A, B and C are three complexes of chromium (III) with the empirical formula
H12O6Cl3Cr
...
Complex A does not react with concentrated H2SO4, whereas complexes
B and C lose 6
...
5% of their original mass, respectively, treatment
with concentrated H 2SO4
...
[Given Molar mass of
H12O6Cl3Cr = 266
...
(H2O)6]Cl3
‘B’ loses 6
...
75
266
...
98g; i
...
1 mole of water
...
100
Hence B = [Cr (H2O)5Cl]Cl2
...
2H2O
...
Rajesh, a student of Class XII Chemistry, wanted silver plating on a
decoration piece, so he visited an electroplating shop
...
He pointed out the poor
115
[Class XII : Chemistry]
quality electroplating
...
This change worked
and silver plating was bright and uniform
...
(b)
Is it a doule salt or a coordination compound? Justify
...
(d)
Mention the values exhibited by Rajesh in the change of electrotype
...
(a)
Write the formulas for the following coordination compounds
...
Formula
Moles of AgCl precipitated per mole of
the compounds with excess AgNO 3
1
...
PtCl4
...
57
...
6H2O
CoCl3
...
(b)
Explain the following :
(i)
(ii)
The -complexes are known for transition elements only
...
Low spin octahedral complexes of nickel are not known
...
(a)
Draw figure to show the splitting of d-orbitals in an octahedral
crystala field and write configuration of Mn+ ion when (i) P>0
(ii) P < 0
(b)
A solution of [Ni(H 2O)6]2+ is green but a solution of [Ni(CN) 4]2– is
colourless
...
(c)
Discuss the nature of bonding in metal carbonyles
...
Haloalkanes are compounds having general formula R–X and haloarenes
are denoted by Ar–X (X = F, Cl, Br and I)
2
...
3
...
Order of reactivity of halogens in Cl2 > Br2 > I2
...
Anti Markownikov’s addition takes place only with HBr in presence of a
peroxide, (benzoyal peroxide)
...
Order of reactivity of hydrohalic acids is HI > HBr > HCl
...
Allylic substitution can be carried out using Cl2 or Br2 at high temperature
...
Halogenation of benzene is an electrophilic substitution reaction
...
FeX3
+ HX ; X = Cl, Br
Order of reactivity in SN1 and SN2 mechanism are as follows –
For S 1
N
3 , 2 , 1 , CH3 X
For S 2
N
SN reactions are characteristic of haloalkanes
...
In case of optically active alkyl halides, SN2 mechanism results in the
inversion of configuration while SN1 mechanism results in racemisation
...
For same alkyl group, boiling points of alkyl halides is in the order :
R I > RBr > R–Cl > R–F
...
For same halogen, boiling points of halides increases with increase in the
size of alkyl group
...
For isomeric halides, boiling point decreases with increase in branching in
hydrocarbon chain
...
C–X bond in aryl halides is shorter, stronger and less polar than in alkyl
halides
...
Aryl halides are much less reactive towards the nucleophilic substitution
(SN) reactions
...
15
...
D
...
is 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane
...
Freon-12 (CF2Cl2) is used as refrigerant
...
CCl4 is used as fire extinguisher under the name pyrene
...
Aryl and vinyl halides do not give precipitate with AgNO3 solution
...
Out of ethyl bromide and ethyl chloride which one has higher boiling point
and why?
2
...
3
...
H
4
...
Which one of the following reacts faster in SN1 reaction and why?
Cl
or
Cl
118
[Class XII : Chemistry]
6
...
Write the IUPAC name of ClCH2C CCH2Br
8
...
H
Write the structure of the following organic compound:
2-Chloro-3-methylpentane
...
Give the IUPAC name of the following :
CH3
H3C
H
Br
H
H3C
11
...
Which one of these is more easily hydrolysed?
12
...
butyl-3-iodoheptane
...
Write the IUPAC name of the following compound
...
Write the structure of the compound 1-Chloro-4-ethylcyclohexane
...
Draw the structure of the following compound:
4-Bromo-e-methylpent-2-ene
...
Which will react faster in S N 2 displacement, 1-bromopentane or
2-bromopentane and why?
17
...
18
...
19
...
20
...
21
...
22
...
butyl-2-methylbenzene
...
Give the IUPAC name of the following compound :
C
C H2
C H 2 Br
C H3
24
...
Predict the order of reactivity of four isomeric bromobutane in SN1 reaction
...
Draw the structure of major monohalogen product in the following reaction:
Fe
+ Cl2
27
...
Write the IUPAC name of
CH3
CH3CH
CH
C
CH3
Br
29
...
Write the IUPAC name of
CH3
CH3
C
CH
CH3
CH3 Cl
31
...
Explain as to why halogens are much less reactive than haloalkanes towards
nucleophilic substitution reactions
...
Which compound in each of the following pairs will react faster in SN2
reaction with OH– and why?
(i)
(ii)
3
...
Discuss the mechanism of SN1 reaction of haloalkanes
...
Suggest a possible mechanism for the following reaction :
EtOH, H2O
n-BuBr + KCN n-BuCN
121
[Class XII : Chemistry]
6
...
CH2Cl or
I or
Cl
Cl
Suggest a possible reason for the following observations:
(i)
(ii)
8
...
Neo-pentyl chloride, (CH3)3C–CH2Cl does not follow SN2 mechanism
...
Cl
Cl
Complete the following chemical equations :
CH3
(i)
(ii)
10
...
the dipole moment of chlorobenzene is lower than that of cyclohexyl
chloride
...
What are ambident nucleophiles? Explain by giving an example
...
Chlorobenzene is extremely less reactive towards nucleophilic substitution
reaction
...
122
[Class XII : Chemistry]
3-Mark Questions
1
...
(iii)
2
...
The treatment of alkyl chloride with aqueous KOH leads to the
formation of alcohol but in the presence of alcoholic KOH, alkene is
the major product
...
CH3
(i)
+ HI
H + HBr
(ii)
H
(iii)
3
...
(ii)
Which compound in the following couples will react faster in SN2
displacement and why?
(a) 1-Bromopentane or 2-bromopentane
(b) 1-Bromo-2-methylbutane or 2-bromo-2-methylbutane
...
How would you differentiate between SN1 and SN2 mechanism of substitution
reactions? Give one example of each
...
Explain why :
(i)
the dipole moment of chlorobenzene is lower than that of cyclohexyl
chloride?
(ii)
alkyl halides though polar are immiscible with water
...
Answer the following :
(i)
(ii)
What is known as racemic mixture? Give an example
...
Haloalkanes easily dissolve is organic solvents
...
CH3–CH–CH3 + OH
– EtOH
CH3–CH=CH2
Br
(ii)
8
...
(i)
(ii)
1-bromo-3-methylbutane, 2-bromo-2-methylbutane,3-Bromo-2methylbutane
...
2-bromo-2-methylbutane, 1-bromopentane, 2-bromopentane
...
(i)
Write a chemical test to distinguish between
(a) chlorobenzene and benzyl chloride
(b) chloroform and carbon tetrachloride
(ii)
10
...
Explain, why is
it so?
124
[Class XII : Chemistry]
1
...
How will you bring about the following conversions?
(i)
benzene to 3-bromonitrobenzene
(ii)
ethanol to but-1-yne
(iii)
1-bromopropane to 2-bromopropane
(iv)
benzene to 4-bromo-1-nitrobenzene
(v)
aniline to chlorobenzene
(vi)
2-methyl-1-propene to 2-chloro-2-methylpropane
(vii)
ethyl chloride to propanoic acid
(viii) but-1-ene to n-butyl iodide
(ix)
(x)
3
...
tert-butyl bromide to isobutyl bromide
...
KCN
A
Li Al H
H3 O+
ether
4
Explain the following reactions with suitable example :
(i)
(ii)
Swarts reaction
...
(iv)
Wurtz-Fitting reaction
(v)
Friedel-Craft’s alkylation reaction
...
Finkelstein reaction
...
Write the major products and name the rule responsible for the formation
of the product
...
Write the difference between
(i)
(ii)
retention and inversion of configuration
...
enantiomers and diastereomers
electrophilic and nucleophilic substitution reactions
...
(iii)
*8
...
n-propyl bromide and isopropyl bromide
...
(CH3)3C–Cl + O H (CH3)3 C–OH
CH3–Cl + OH– CH3–OH
Which compound in each of the following pairs will react faster in SN2
reaction with OH– and why?
(i)
CH3Br or CH3I
(ii)
(CH3)3 CCl or CH3Cl
*10
...
(vii)
11
...
Give reasons for the following :
(i)
The bond length of C–Cl bond is larger in haloalkanes than that in
haloarenes
...
(iii)
tert-butyl bromide has lower boiling point than n-butyl bromide
...
(v)
sulphuric acid is not used in the reaction of alcohol with Kl
...
(vii)
haloalkanes undergo nucleophilic substitution reaction easily but
haloarenes do not undergo nucleophilic substitution under ordinary
conditions
...
(ix)
Grignard reagent should be prepared under anhydrous conditions
...
*(xi) neopentyl bromide undergoes nucleophilic substitution reactions very
slowly
129
[Class XII : Chemistry]
*(xii) vinyl chloride is unreactive in nucleophilic substitution reaction
...
[Hint : The hydrolysis reaction occurs by SN1 pathway
...
12
...
(Increasing order
of dipole moment
...
bromomethane, chloromethane, dichloromethane
...
o,m
...
Write the different products and their number formed by the monochlorination
of following compounds :
(i)
CH3CH2CH2CH3
(ii)
(CH3)2CHCH 2CH3
(iii)
(CH3)2CHCH(CH 3)2
[Hint : (i) Two, (ii) four, (iii) three
130
[Class XII : Chemistry]
*14
...
(b)
In the following reaction :
major and minor products are :
(i)
(ii)
(iii)
(iv)
Ans
...
Give one use of each of following :
(i)
Freon-12
(ii)
DDT
(iii)
Carbon tetrachloride
(iv) Iodoform
**16
...
Give
mechanism for the reaction
...
]
**17
...
A is optically
active
...
Benzoic acid, terephthalic and
p-bromobenzoic acid were obtained on oxidation of A, B and C respectively
...
**18
...
Both alkenes on hydrogenation give 2, 3-dimethylbutane
...
132
[Class XII : Chemistry]
**19
...
The compound B on
hydrolysis with dilute HCl gives compound C
...
Identify A, B and C
...
: (A) CH3CH2CH2Cl, (B) CH3CH2CH2CN, (C) CH3CH2CH2CONH2
*20
...
Which nomenclature is not according to IUPAC system
...
Primary alkyl halide (A) C4H9Br reacted with alc
...
‘B’ when
reacted with HBr to give ‘C’, which is an isomer of ‘A’
...
Give the structural
formulas of ‘A’ to ‘D’ and write the chemical equations of reactions involved
...
Write the structures and names of the compounds formed when compound
‘A’ with molecular formula, C7H8 is treated with Cl2 in the presence of FeCl3
...
Identify the products A and B formed in the following reaction:
(a)
CH3 CH2 CH = CH
Hint: A
CH3 CH2 CH
CH3 CH2
+
CH
CH3 + HCl
A+B
B
CH2 CH3
Cl
CH3 CH2CH2
CH CH3
Cl
+
CH3 CH2 CH2 CH CH3
CH2 CH3
Less Stable
(4 Hyperconjugative Structures)
More Stable
(5 Hyperconjugative Structures)
Amount of B is slightly more than A
26
...
**27
...
Give the
structure of the hydrocarbon
...
Name the alkene which will yield 1-chloro-1-methylcyclohexane by its
reaction with HCl
...
CH2
Hint:
29
...
(i)
1-Bromobutane
...
Why can aryl halides not be prepared by reaction of phenol with HCl in the
presence of ZnCl2?
31
...
CH2Cl
(B)
Allyl chloride is hydrolysed more readily than n-propyl chloride
...
(i)
How do polar solvents help in the first step in SN1 mechanism?
Elimination reactions (especially -elimination) are as common as the
nucleophilic substitution reaction in case of alkyl halides
...
Hint : For elimination reactions : - strong base, high temperature
For substitution reactions : - weak ase, low temperature
alc
...
How will you obtain monobromobenzene from aniline?
35
Aryl halides are extremely less reactive towards nucleophilic substitution
...
(a) In primary, secondary and teritary alcohols the –OH group is bonded
to sp3 hybridised C atom
...
(c) In benzylic alcohols, –OH is attached to a sp3 hybridised C atom next
to an aromatic ring
...
2
...
3
...
4
...
5
...
EWG : –NO2, –X, –CN, –COOH etc
...
6
...
7
...
8
...
9
...
137
[Class XII : Chemistry]
10
...
11
...
12
...
13
...
14
...
OH
O
CH3
C
or CH3
CH
1-Mark Questions
1
...
Write the IUPAC name of
H3C
CH
CH2
3
...
4
...
H3C
CH
CH
CH2
CH2
CH3
OH
5
...
6
...
7
...
8
...
9
...
Draw the structure of 2,6-dimethylphenol
...
Draw the structure of hex-1-en-3-ol compound
...
Draw the structural formula of 2-methylpropan-2-ol molecule
...
Write the IUPAC name of the following compound:
H 3C
CH
CH
CH2
CH
CH3
OH
14
...
Write the IUPAC name of the following:
H 3C
C
C
CH2OH
CH3 Br
2-Mark Questions
1
...
propene to propan-1-ol
phenol to salicylic acid
How are the following conversions carried out?
(i)
(ii)
3
...
How are the following conversions carried out?
(i)
(ii)
4
...
Phenols are more acidic than alcohols?
The boiling points of ethers are much lower than those of the alcohols
of comparable molar masses?
Give reason for the following:
(i)
m-Aminophenol is a stronger acid that o-aminophenol
...
139
[Class XII : Chemistry]
6
...
(i)
Propanol has higher boiling point than butane
...
7
...
8
...
OH + SOCl2
(i)
CH2OH
+ HCl
(ii)
HO
9
...
(i)
phenol and benzoic acid
(ii)
1-propanol and 2-propanol
10
...
11
...
Benzyl chloride to benzyl alcohol
Methyl magnesium bromide to 2-methylpropan-2-ol
...
Picric acid from phenol?
2-methylpropanol from 2-methylpropene?
Give a chemical test to distinguish between the following pair of compounds
(i)
(ii)
14
...
Explain the mechanism of acid catalysed hydration of an alkene to form
corresponding alcohol
...
Explain the following behaviours:
(i)
(ii)
16
...
o-nitrophenol is more acidic than o-methoxyphenol
...
Name the reagents which are used in the following conversions
...
(i)
Describe the mechanism of acid catalysed dehydration of ethanol
to yield ethene
...
Butan-2-one to butan-2-ol
(iii)
2
...
Explain the mechanism of the following reactions
...
(iii)
4
...
Acid catalysed hydration of an alkene forming an alcohol
...
phenol to benzoquinone?
Propene to propan-2-ol?
(a)
Write the IUPAC name of the following
CH3
OH
CH3
141
[Class XII : Chemistry]
(b)
(i)
Phenol is a stronger acid than alcohol
...
Give reason for the following:
Alcohols are comparartively more soluble in water than the
corresponding hydrocarbons
...
(iii)
7
...
The boiling point of ethers are lower than isomeric alcohols
...
(iii)
8
...
Phenyl methyl ether reacts with HI to give phenol and methyl iodide
and not iodobenzene and methyl alcohol
...
(iii)
Propan-2-ol from propene
...
(ii)
9
...
Write Kilbe’s reaction with an example
...
A compound A (C2H6O) on oxidation by PCC gave B, which in treatment
with aqueous alkali and subsequent heating furnished C
...
Deduce the structure of A, B and C
...
Draw the structure and name the product formed if the following alcohols
are oxidised
...
(i)
CH3CH2CH2CH2OH
(ii)
Butan-2-ol
(iii)
Methylpropan-2-ol
...
Describe the following reactions with example :
(i)
(ii)
Acid catalysed dehydration of alcohols at 443K
...
(v)
Kolbe’s reaction
(vi)
2
...
Complete the following reactions :
(i) CH3MgBr
+
(ii) H /H2O
Cu/573K
143
[Class XII : Chemistry]
(i) NaOH,
(ii) H
3
...
(iii)
phenol is treated with conc
...
(iv)
4
...
How will you convert
(i)
propene to propan-l-ol
...
(ix)
toluene to benzyl alcohol
(x)
1-propoxypropane to propyl iodide
(xi)
ethyl bromide to ethoxyethane
(xii)
methyl bromide to 2-methoxy-2-methylpropane
(xiii) ethyl bromide to ethoxybenzene
(xiv) ethanol to benzyl ethyl ether
...
(xvi) phenol to 2,4,6-trinitrophenol
...
Identify the missing reactant or product A to D in the following equations:
145
[Class XII : Chemistry]
6
...
Write the mechanism for following reactions :
(acid catalysed hydration of alkenes)
+
(ii)
CH3 – CH2 – OH
H
443 K
CH2 = CH2
(acid catalysed dehydration of alcohols)
+
(iii)
CH3CH2OH
H
CH3CH2OCH2CH3
413 K
(acid catalysed nucleophilic substitution reaction)
(iv)
(v)
8
...
7°
...
(iii)
Phenols are more acidic than alcohols
...
146
[Class XII : Chemistry]
(v)
Phenol is more reactive towards electrophilic substitution reaction
than benzene
...
The following is not an appropriate method for the preparation of
1-methoxy-4-nitrobenzene;
(viii) Write the suitable reaction for the preparation of
1-methoxy-4-nitrobenzene
(ix)
o-nitrophenol is steam volatile but p-nitrophenol is not
...
(xi)
phenyl methyl ether reacts with HI to form phenol and iodomethane
and not iodobenzene and methanol
...
(xiii) alcohols can act as weak base as well as weak acids
...
(xv)
9
...
Arrange the following in the increasing order of property shown :
(i)
methanol, ethanol, diethylether, ethyleneglycol
...
(Acid strength)
(iii)
dimethylether, ethanol, phenol
...
(Acid strength)
147
[Class XII : Chemistry]
10
...
(i)
(ii)
methanol and ethanol
(iii)
cyclohexanol and phenol
(iv)
propan-2-ol and 2-methylpropan-2-ol
(v)
phenol and anisole
(vi)
ethanol and diethyl ether
(vii)
11
...
**12
...
Compound A when dehydrated with
conc
...
Treatment of C with aqueous
H2SO4 gives compound D (C4H10O) which is an isomer of A
...
Identify
A, B, C and D and write their structures
...
:
[A] : (CH3)2CHCH2OH
[B] : CH3CH(CH3)COOH
[C] : (CH3)2C = CH2
[D] : (CH3)3C – OH
**13
...
When A is treated with NaOH
and CO2 at 400 K under pressure, compound B is obtained
...
Deduce the structure of A, B, C and D
...
An ether A (C5H12O) when heated with excess of hot concentrated HI
produced two alkyl halides which on hydrolysis from compounds B and C
...
Deduce the structures of A, B, C, D and E
...
: (A)
(B)
CH3CH2OH
(C)
CH3CHOHCH 3
(D)
CH3COOH
(E)
CH3COCH3
**15
...
Phenol, C6H5OH when it first reacts with concentrated sulphuric acid, forms
Y • The compound, Y is reacted with concentrated nitric acid to form Z
...
HNO3
...
:
NO2
Phenol is not reacted directly with conc
...
Synthesise the following alcohols from suitable alkenes
...
How are the following ethers prepared by williamson synthesis?
(a)
Ethoxybenzene
(b)
2-methoxy-2-methylpropane
**19
...
Both ‘B’ & ‘C’ gives same product ‘D’ when distilled
with Zn dust
...
The sodium
salt of ‘E’ on heating with sodalime gives ‘F’ which may also be obtained
by distilling ‘A’ with Zn dust
...
150
[Class XII : Chemistry]
Unit - 12
ALDEHYDES, KETONES AND
CARBOXYLIC ACIDS
POINTS TO REMEMBER
1
...
2
...
3
...
4
...
(ii)
HCHO > RCHO > R CO R
...
5
...
6
...
This is known as Aldol condensation
...
Aldol condensation involves carbanion as intermediate
...
Aldehydes with no H atoms undergo Cannizzaro’s reaction
...
Ketones react with dihydric alcohols to form cyclic ketals
...
Monocarboxylic acids having (C12–C18) carbon atoms, are called fatty acids
...
Boiling points of carboxylic acids is greater than corresponding alcohols
...
Even membered carboxylic acids have higher melting point than odd
members preceeding or following it
...
–COOH group is not a true carbonyl group because of resonance
...
16
...
17
...
A stronger acid always has
higher Ka but a lower pKa value
...
–COOH group is meta-directing in electrophilic substitution reaction
...
Name the compound according to IUPAC system
...
2
...
Write IUPAC name of CH3CH(CH3)CH2C(CH3)2COCH3
4
...
3
H 3C
CH
CO
CH3
CH3
CH3
5
...
OH
C
OH
O
6
...
7
...
Write the IUPAC name of the following :
CH3
CH3
C
CH2COCH3
OH
9
...
10
...
11
...
Write the IUPAC name of the following :
(CH3)2CH
CH2
C
CH(CH3)2
O
13
...
14
...
15
...
Write the IUPAC name of the compound
...
C
CH2
CH3
Write the name of :
CH3
C
O
CH
C
CH3
CH3
18
...
19
...
153
[Class XII : Chemistry]
20
...
Give a chemical test to distinguish between benzophenone and
acetphenone
...
Arrange the following compounds in an increasing order of their reactivity
towards nucleophilic addition reactions: ethanal, propanal, propanone,
butanone
...
Illustrate the following reaction giving a suitable example
...
24
...
25
...
Illustrate the Clemmensen reduction reaction by giving a suitable example
...
Draw the structure of the compound 4-methylpent-3-en-2-one
...
Write the structure of p-methylbenzaldehyde molecule
...
How would you bring about the following conversions?
(i)
(ii)
30
...
Acetphenone to 2-phenyl-2-butanol
Propene to acetone
...
Give a plausible explanation for each one of the following :
(i)
There are two –NH2 groups in semicarbazide
...
(ii)
Cyclohexanone forms cyanohydrins in good yield but 2,2,
6-trimethylcyclohexanone does not
...
An organic compound A contains 69
...
63% hydrogen and
rest oxygen
...
It does not
reduce Tollens’ reagent but forms an addition compound with sodium
hydrogensulphite and gives positive iodoform test
...
Derive the structure of
compound A
...
Write the structures of the main products of following reactions
...
AlCl3
CS2
2+
(ii)
H3C
C
C
H
Hg
...
(i)
Descrie the mechanism of the addition of Grignard reagent to the
carbonyl group of a compound to form an adduct which on hydrolysis yield
an alcohol
...
(i)
36
...
(ii)
How would you bring about following conversions? Write complete
equations in each case
...
155
[Class XII : Chemistry]
5-Mark Questions
37
...
O3
2
O
Zn/2HO
CH2
(b)
...
KOH, heat
(ii)
Describe the following reactions :
(a)
(b)
38
...
(c)
(ii)
Aldehydes are more reactive than ketones
...
Give chemical tests to distinguish between
(a)
Acetaldehyde and benzaldehyde
...
39
...
B reacts with HBr to form the compound
C
...
Identify A to E
...
An organic compound A on treatment with acetic acid in the presence of
sulphuric acid produces an ester B
...
C with
50% KOH followed by acidification with dil
...
D with
156
[Class XII : Chemistry]
PCl5 followed by reaction with ammonia gives E
...
Identify the compounds A, B, C, D and E
...
(i)
How ill you prepare the following compounds starting with benzene?
(a)
(ii)
Benzaldehyde
(b)
Acetophenone
How will you bring about the following conversions?
(a)
Propanone to propene
...
(c)
Benzaldehyde to benzophenone
...
A ketone A(C4H8O) which undergoes a haloform reaction gives compound
B on reduction
...
D on hydrolysis with zinc dust gives only E
...
Write the reactions involved
...
(i)
Identify A, B and C in the following sequence of reactions :
(i) C H MgCl
Conc
...
Conc
...
B does not reduce Fehling’s reagent but gives a yellow ppt
...
Deduce the structures of A, B and C
...
(i)
An organic compound with molecular formula C9H10O forms 2,4DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro’s
reaction
...
Identify the compound
...
(i)
Although phenoxide ion has more number of reasonating structures
than carboxylate ion, carboxylic acid is stronger acid than phenol
...
(ii)
How will you bring about the following conversions?
(a)
Propanone to propane
(b)
Benzoyl chloride to benzaldehyde
(c)
Ethanal to but-2-enal
CARBOXYLIC ACIDS
1-Mark Questions
1
...
2
...
Arrange the following compounds in increasing order of their acid strength:
(CH3)2CHCOOH, CH3CH2CH(Br)COOH, CH3CH(Br)CH2COOH
4
...
C
C
CH
CH
Write IUPAC name of
C
OH
COOH
Br
Cl
158
[Class XII : Chemistry]
6
...
7
...
8
...
9
...
Benzoic acid to m-nitrobenzyl alcohol
...
How are the following conversions carried out ?
(i)
(ii)
11
...
Monochloroethanoic acid is a weaker acid than dichloroethanoic acid
...
Give chemical tests to distinguish between
(i)
(ii)
13
...
(i)
KMnO4, H2SO4
C
(ii)
14
...
Account for the following :
(i)
(ii)
Electrophilic substitution in benzoic acid takes place at meta-position
...
Chloroacetic acid has higher pKa value than acetic acid
...
Describe how the following conversions can be brought about
...
(iii)
17
...
Bromobenzene to benzoic acid
...
But-2-enal from ethanal
Benzoic acid from ethyl benzene
Complete the following equations :
COOH
SOCl2
Heat
(a)
COOH
(b)
(c)
19
...
Identify A, B and C in the sentence :
COOH
B Strong C
heating
A Heat
+ NH3
COOH
5-Mark Questions
21
...
formula C8H16O2) was hydrolysed with
dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C)
...
On dehydration (C)
gives but-2-ene
...
22
...
B on oxidation gives an acid (C7H6O2)
which on treatment with a mixture of conc
...
B on treatment with conc
...
Deduce the structures of A, B, C, D and E
...
(i)
How are the following obtained?
(a)
(b)
(ii)
Benzoic acid from ethyl benzene
...
Complete each synthesis by givintg the missing material reagent or
products
...
Pd BaSO
O
C
(b)
+
...
AlCl3
O
C
(c)
+
...
(i)
Arrange the following compounds in an increasing order of their
indicated property :
(a)
(b)
(ii)
Benzoic acid, 4-nitrobenzoic acid, 3, 4-dinitrobenzoic acid,
4-methoxybenzoic acid, (acid strength)
...
How will you bring about the following conversions?
(a)
Propanone to propene
(b)
Benzoic acid to benzaldehyde
(c)
Bromobenzene to 1-phenylethanol
...
Compound A (C6H12O2) on reduction with LiAlH4 yields two compounds B
and C
...
The latter on catalytic
hydrogenation gave ‘C
...
Deduce the structures of A, B, C, D and E
...
Identify A to E in the following reactions :
COOH
Conc
...
H3SO4
27
...
(a)
Hell Volhard Zelinsky reaction
...
How are the following conversions carried out?
(a)
Ethyl cyanide to ethanoic acid
(b)
Butan-1-ol to butanoic acid
(c)
Methylbenzene to benzoic acid
...
(a)
How will you convert the following :
(i)
(ii)
Ethanal to 2-hydroxypropanoic acid
(iii)
(b)
Propanone to propan-2-ol
Toluene to benzoic acid
...
(a)
Pentan-2-one and Pentan-3-one
Ethanal and propanal
Write the products of the following reactions :
CH3
C
(i)
CH3
Zn–Hg
Conc
...
Explain the following reactions giving one example of each :
(i)
Rosenmund reduction reaction
(ii)
Stephen reduction reaction
(iii)
Etard reaction
(iv)
Gatterman-Koch reaction
(v)
Aldol condensation
(vi)
Cross aldol condensation
(vii)
Cannizzaro reaction
(viii) Decarboxylation reaction
(ix)
(x)
Hell-Volhard-Zelinsky reaction
(xi)
Clemmensen reduction
(xii)
Wolff-Kishner reduction
(xii)
2
...
How will you convert?
(i)
Isopropyl chloride to 2-methylpropionaldehyde
...
(ix)
methyl magnesium bromide to ethanoic acid
(x)
benzoic acid to benzyl chloride
(xi)
acetone to chloroform
(xii)
acetylene to acetic acid
(xiii) formaldehyde to propanol
(xiv) acetophenone to 2-phenylbutan-2-ol
(xv)
ethanal to but-2-enal
(xvi) benzoyal chloride to benzeldehyde
...
164
[Class XII : Chemistry]
3
...
KOH
(iv)
2HCHO
(v)
2
CH3COOH
(ii) H O
(i) Br P
2
CHO
(vi)
HNO3/H 2SO4
273–283 K
(vii)
(viii)
(ix)
165
[Class XII : Chemistry]
(x)
(xi)
(i)
(xii)
(ii) H2O
(xiii)
4
...
2,4-DNP derivative
Oxime
Arrange the following in the increasing order of the property indicated
(i)
CH3CHO, HCHO, CH3COCH3, C6H5CHO (reactivity towards HCN)
(ii)
propan-1-ol, propanone, propanal (boiling point)
8
...
Give one chemical test to distinguish between following pair of compounds:
Write the chemical reactions involved
...
propan-2-ol and propanone
ethanal and propanal
...
(ii)
Benzaldehyde does not give Fehling’s test
...
(iv)
p-nitrobenzaldehyde is more reactive than benzaldehyde towards
nucleophilic addition reactions
...
(vi)
For the formation of ethyl acetate from acetic acid and ethanol in
presence of sulphuric acid, the reaction mixture is heated to remove
water as fast as it is formed
...
(viii) Monochloroethanoic acid is a weaker acid than dichloroethanoic acid
...
(x)
Aldehydes are more reactive towards nucleophilic reagents than
ketones
...
167
[Class XII : Chemistry]
(xii)
Formic acid reduces Tollens’ reagent
...
(xiv) Carboxylic acids do not give characteristic reactions of carbonyl group
...
(xvi) tert-butylbenzene cannot be oxidised with KMnO4
...
However, only one
–NH2 group is involved in the formation of semicarbazones
...
(xx)
**8
...
NH2/OH– in Glycol,
H2/Ni and NaBH4
...
Y ou are gi
ven f
our dif
f erent reagent Z n-H g/ C l N H 2
s
H ,
[Hint : OH group and alkene are sensitive groups to HCl, so clemmeson
reduction cannot be used
...
**9
...
It does not reduce Tollens’ reagent but forms an addition
compound with sodium hydrogen sulphite
...
On oxidation with KMnO4, [A] forms
two acids D and E having molecular formula C3H 6O 2 and C 2H 4O 2
respectively
...
A : CH3CH2CH2COCH3
B : CHI3
C : CH3CH2CH2COONa
D : CH3CH2COOH
E : CH3COOH
**10
...
NaOH form A which
on heating changes to B
...
Reduction
of C with DIBAL- H yields D which on hydrolysis gives E
...
[Ans
...
Identify the missing reagent/products in the following reactions :
12
...
NaOH
HCOONa + (CH3)3 CCH2OH
*13
...
Ozonolysis of ‘B’ gives compounds ‘C’ and ‘D’
...
Compound ‘D’ on reaction
with KOH gives -unsaturated ketone having the following structure:
169
[Class XII : Chemistry]
CH3
—
Ph—C — CHCOPh
*14
*15
Arrange the following acids in the order of increasing acid strength
(i)
formic acid, benzoic acid, acetic acid
(ii)
(iii)
16
...
Why?
[Ans
...
]
170
[Class XII : Chemistry]
*17
During reaction of carbonyl compound with 2,4-DNP reagent, the pH of the
reaction mixture has to be maintained between 3 and 4
...
: H+ ions increase the electrophilicity of carbonyl carbon
...
After
protonation –N+H3 group does not act as nucleophile
...
An aromatic compound X with molecular formula C9H10 gives the following
chemical tests :
(i)
forms 2,4-DNP derivative
(ii)
reduces Tollens’ reagent
(iii)
undergoes Cannizzaro reaction
(iv)
On vigorous oxidation gives 1,2-benzenedicarboxylic acid
...
Also write the reactions involved
in the formation of above mentioned products
...
...
Iodoform can be prepared from all except
...
(ii)
Write structure of 4-chloropentan-2-one
...
Ethyl methyl ketone
Isopropyl alcohol
Write structure of 3-methylbutanal
...
An alkene ‘A (Mol
...
Compound ‘B’ gives positive Fehling’s test and
also forms iodoform on treatment with I2 and NaOH
...
Identify the compounds A, B,
and C
...
O
CH3
[A] = CH3 CH
C
CH3
[B] = CH3 CHO
171
[C] = CH3 C
CH3
[Class XII : Chemistry]
**22
...
It gives a yellow precipitate of compound ‘B’ on treatment with
iodine and sodium hydroxide solution
...
On drastic ooxidation with potassium permangnate it
forms a carboxylic acid ‘C’ (Molecular formula C H6O2), which is also formed
7
along with the yellow compound in the above reaction
...
COOH
COCH3
(A) =
(B) = CHI3
(C) =
**23
...
Which isomers will react faster with HCN and why? Explain
the merchanism of the reaction also
...
Addition of strong acid inhibits the reaction because the formation of CN–
from weak acid, HCN is prevented
...
When liquid ‘A’ is treated with a freshly prepared ammoniacal silver nitrate
solution, it gives bright silver mirror
...
Liquid ‘B’ also forms a
white crystalline solid with sodium hydrogensulphite but it does not give
test with ammoniacal silver nitrate
...
(A) = Aldehyde R — CHO
R
(B) = Methyl Ketone
C
O
H3C
172
[Class XII : Chemistry]
Unit - 13
AMINES
POINTS TO REMEMBER
1
...
2
...
Gabriel phthalimide synthesis can’t be used for the preparation of 2° and
3° amines
...
4
...
5
...
(iii)
6
...
In non-aqueous medium or gaseous phase the order is 3° > 2° > 1°
...
(ii)
ERGs like –CH3, –OR, –NH2 etc
...
decrease the basic strength
...
7
...
8
...
9
...
10
...
11
...
173
[Class XII : Chemistry]
12
...
13
...
14
...
1-Mark Questions
1
...
2
...
Give a chemical test to distinguish between aniline and N-methyl aniline
...
Illustrate the coupling reaction with an example
...
Like ammonia, amines are good nucleophiles, why?
6
...
Given a chemical test to distinguish a primary and a secondary amine
...
What happens when aniline is treated with bromine?
9
...
10
...
11
...
Arrange in increasing order of their basic strength
...
13
...
Write a chemical equation to illustrate the ammonolysis reaction
...
Give a chemical test to distinguish between benzhylamine and aniline
...
Rearrange the following in the increasing order of their basic strength
...
Write IUPAC name of H2N—CH2—CH2—CH=CH2
...
Why electrophilic substitution takes place more readily in aromatic amine
than benzene
...
Why can primary aromatic amines be not prepared by Gabriel phthalimide
synthesis?
20
...
Write the structure of N-methylethanamine
...
Account for the following :
(i)
(ii)
23
...
CH3CONH2 is a weaker base than CH3CH2NH2
...
Aromatic amines are less basic than aliphatic amines
...
(b)
24
...
Write the chemical reaction for the reduction of nitroethane by LiAlH4
...
xH2O)
(iii)
26
...
Aniline does not undergo Friedel Crafts reaction
...
C6H5NH2, (C2H5)2NH, (C2H5)3N and CH3NH2
27
...
175
[Class XII : Chemistry]
28
...
Amines are less acidic than alcohols of comparable molecularmasses
...
How are the following conversions carried out?
(i)
(ii)
30
...
Write equations for
(i)
(ii)
31
...
nitrobenzene to aniline
...
Illustrate the following with an example of reaction in each case
...
Sandmeyer’s reaction
Coupling reaction
Convert:
(i)
(ii)
34
...
aniline to benzonitrile?
ethanamine to ethanoic acid?
Describe the following reactions by giving the relevant chemical equation
in each case
...
Carbylamine reaction
Hoffmann’s bromamide reaction
Complete the following equations,
(a)
C 6H5N2+Cl–
(b)
C6H5NH2 + Br2 (aq)
+ H3PO2 + H2O
176
[Class XII : Chemistry]
3-Mark Questions
37
...
(i)
(ii)
Preparation of benzonitrile from aniline
...
Preparation of ethylamine from acetaldehyde
...
How could you carried out the following conversions?
(i)
(ii)
An alkyl halide to a quaternary ammonium salt
(iii)
39
...
(iii)
40
...
Primary amines have higher boiling points than tertiary amines
...
(i)
(ii)
Aniline to benzenediazonium chloride
(iii)
41
...
C6H5NH2 + CH3COCl
C2H5NH2 + HNO2
Complete the following chemical equations
...
KOH
177
[Class XII : Chemistry]
43
...
(i)
(ii)
Acetylation reaction
(iii)
44
...
Complete the following :
(i)
NaCN
Reduction
CH3CH2Cl A A
(ii)
Ni/H2
C6H5N2+Cl– + H3PO2 + H2O
(iii)
R
C
O
45
...
(i)
(ii)
Benzyl chloride to 2-phenylethanamine
(iii)
46
...
C
Give the structures of products A, B and C in the following reactions :
(i)
LiAlH
KCN
HNO
4
2
CH6CH5Br A B C
NH
NaOH Br
CHCl Alc
...
Giving an example of each, describe the following reactions :
(i)
Hoffman bromamide reaction
(ii)
Gabriel phthalimide synthesis
(iii)
Gatterman reaction
(iv)
Coupling reaction
(vi)
Carbylamine reaction or isocyanide test
(vii)
Acetylation of aniline
...
Describe the Hinsberg’s test for identification of primary, secondary and
tertiary amines
...
3
...
(i)
(ii)
C2H5NH2, (C2H5)2NH, (C2H5)3N and CH3NH2
...
(iii)
Aniline, p-toluidine, p-nitroaniline
...
(iv)
C2H5OH, (CH3)2NH, C2H5NH2
(v)
4
...
C6H5NH2, (C2H5)2NH, C2H5NH2 (Increasing order of solubility)
(Boiling point)
Identify A and B in the following reactions :
(i)
373K
OH–
(ii)
5
...
(v)
methyl bromide to ethanamine
(vi)
benzenediazonium chloride to nitrobenzene
179
[Class XII : Chemistry]
(vii)
ethylamine to methylamine
(viii) benzene to sulphanilic acid
(ix)
hexanenitrile to 1-aminopentane
...
(xi)
benzene to 3-bromophenol
...
(xiii) benzamide to toluene
...
6
...
Identify the missing reagent/product in the following reactions :
180
[Class XII : Chemistry]
8
...
methylamine and dimethylamine (Hint : by carbylamine test)
ethanol and ethanamine (by carbylamine test)
Write structure of reagents/compounds (A to F) in following sequences of
reactions
...
HNO (conc
...
2
4
H Pt
F
2
D E C6H5NHCOCH3 CH3COOH
10
...
KOH Br
NaNO HCl
D
2
2
A B C
0 5 C
Cl Fe
H Pt
2
2
E F C6H5 CH2NH2
11
...
(ii)
the quaternary ammonium salts having four different alkyl groups are
optically active
...
(iv)
aniline cannot be prepared by Gabriel phthalimide synthesis
...
(vi)
ethylamine is soluble in water but aniline is not
181
[Class XII : Chemistry]
(vii)
amines are soluble in dilute HCl
...
(ix)
1° amines have higher boiling points than 2° amines which in turn,
are higher boiling than 3° amines
...
33 while that of ammonia is 4
...
(xi)
aniline does not undergo Friedel-Crafts reaction
...
(xiii) sulphanilic acid is soluble in water
...
(xv)
(xvi)
12
...
al hough am i
t
no group i O –
s
and p-directing in aromatic electrophilic
substitution reactions, aniline on nitration gives a substantial amount
of m-nitroaniline
...
**13
...
Compound A on reaction with benzene sulphonyl chloride forms a product
which is soluble in NaOH
...
Identify A, B and C
...
: (A) CH3CH2CH2NH2 (B) CH3CH2NHCH3 (C) (CH3)3N]
*14
...
Compound A on treatment with Ni/H 2 forms B
...
When B is warmed
with chloroform and NaOH, a foul smelling compound C formed
...
[Ans
...
An organic compound [A] C3H6O2 on reaction with ammonia followed by
heating yields B
...
NaOH gives
compound C (C2H7N)
...
Identify A, B, C, D and the write the
equations of reactions involved
...
(A) CH3CH2COOH
(D) CH3CH2NC
...
CH3
(i) NaNO2 + HCl, 273-278K
(ii) H3PO2
A
NO2
NH2
17
...
Why is benzene diazonium chloride not stored and is used immediately
after its preparation?
19
...
Explain why MeNH2 is stronger base than MeOH?
21
...
Under what reaction conditions (acidic/alkaline), the coupling reaction of
arylldiazonium chloride with aniline is carried out?
23
...
24
...
CH3CH2CH3, CH3CH2NH2, CH3CH2OH
25
...
Identify Z
...
A primary amine, RNH2 can be reacted with CH3–X to get secondary
amine, R–NHCH3 but the only disadvantage is that 3° amine and quaternary
ammonium salts are also obtained as side products
...
Complete the following reaction
...
Why is aniline soluble in aqueous HCl?
29
...
CONH2
NH
30
...
O
Cl
KCN
A
H2/Pd
B
**31
...
3
On reacting with NaNO2 and HCl followed by treatment with water,
compound ‘C’ yields an optically active alcohol, ‘D’
...
Identify compounds ‘A’ to ‘D’
...
Hint: (A) = CH3 — CH = CH — CH3
(B) = CH3 — CH2 — CH — CH3
Cl
(C) = CH3 — CH2 — CH — CH3
NH2
(D) = CH3 — CH2 — CH — CH3
OH
**32
...
On reacting
with CHCl3 and alcoholic potash ‘A’ produces an obnoxious smell due to
184
[Class XII : Chemistry]
the formation of compound ‘C’
...
With NaNO2 and
HCl, ‘A’ forms compound ‘E’ which reacts with phenol in alkaline medium
to give an orange dye ‘F’
...
Hint:
NH2
+
(A)
–
N2Cl
(B)
O
NC
(C)
NH
(D)
S
O
+
–
N2Cl
(E)
N=H
(F)
OH
**33
...
CH3
CH3
CH3
(CH3CO)2O
NO2
(CH3CO)2O
Pyridine
1
Pyridine
2
NHCOCH3
NH2
CH3
3
CH3
5
4
NaNO2/HCl
NO2
NO2
NH2
Hint: 1:
Sn/HCl or Fe/HCl
NHCOCH3
2:
H3C
3:
NO2
H+/H2O or H3O+
N
4:
H 3C
+
NCl
NO 2
185
–
5: H3PO2/H2O
[Class XII : Chemistry]
Unit - 14
BIOMOLECULES
POINTS TO REMEMBER
1
...
2
...
3
...
They can’t be
hydrolysed to simpler carbohydrates
...
Glycocidic linkage : The oxide linkage which connects the monosaccharides units in oligosaccharides or polysaccharides
...
Sucrose on hydrolysis gives glucose and fructose
...
Maltose on hydrolysis gives only glucose
...
Loctose on hydrolysis gives one molecule of glucose and one molecule of
galactose
...
Mutarotation : The process involving the gradual change in the optical
rotation of either optically active form of carbohydrates in aqueous solution
to that of equilibrium mixture
...
Anomers : The pair of diastereomers of aldoses which differ in configuration
at C1 atom
...
-Amino acids : The organic compounds containing –COOH group and
–NH2 group at the -carbon atom
...
11
...
Proteins are polymers of -amino
acids which are connected to each other by peptide bonds
...
Denaturation : It is the process that brings about changes in the physical
as well as biblogical properties of the proteins
...
186
[Class XII : Chemistry]
13
...
14
...
The base uracil is present only in
RNA while the base thymine is present only in DNA
...
15
...
16
...
17
...
18
...
19
...
20
...
21
...
They may be classified as water soluble or fat soluble
...
Name polysaccharide which is stored in the liver of animals
...
What structural feature is required for a carbohydrate to behave as reducing
sugar?
[Hint : The carbonyl group of any one monosaccharide present in
carbohydrate should be free]
3
...
Name the enantiomer of D-glucose
...
Give the significance of (+)-sign in the name D-(+)-glucose
...
187
[Class XII : Chemistry]
6
...
[Hint : ‘D’ Signifies that –OH group on C-5 is on the right hand side]
7
...
Give reason
...
8
...
]
9
...
10
...
11
...
12
...
(H2NCH2COOH)
...
Name the enzyme which catalyses the hydrolysis of maltose into glucose
...
Give reason : Amylase present in the saliva becomes inactive in the
stomach
...
How would you explain the amphoteric behavior of amino acids
...
]
16
...
17
...
18
...
Explain
...
]
19
...
What does this fact suggest about the structure
of RNA
...
188
[Class XII : Chemistry]
20
...
Mention the number of hydrogen bonds between adenine and thymine
...
A child diagnosed with bone deformities, is likely to have the deficiency of
which vitamin?
23
...
List two important functions of proteins in human body
...
Name the vitamin responsible for coagulation of blood
...
Except vitamin B12, all other vitamins of group B, should be supplied regularly
in diet
...
How is glucose prepared commercially?
28
...
What is the difference between an oligosaccharide and a polysaccharide?
30
...
SA (I) TYPE QUESTIONS (2 - Marks Questions)
1
...
2
...
3
...
(i)
Acetylation of glucose with acetic anhydride gives glucose pentaacetate
...
(ii)
Explain why glucose pentaacetate does not react with hydroxylamine?
[Hint : The molecule of glucose pentaacetate has a cyclic structure in
which –CHO is involved in ring formation with OH group at C–5]
5
...
(i)
(ii)
7
...
(i)
Ribose
(ii) Maltose
(iii) Galactose
(iv) Lactose
8
...
189
[Class XII : Chemistry]
9
...
10
...
(i)
HOOC–CH2–CH (NH2) COOH
(ii)
C6H5–CH2–CH(NH2) COOH
(iii)
H2N–(CH2)4–CH(NH 2)–COOH
(iv)
HN = C–(CH2)3–CH(NH2)COOH
NH2
11
...
12
...
[Hint : Hydrogen bonds, disulphide linkages, vander Waals and electrostatic
forces of attraction
...
Classify the following as globular or fibrous proteins
...
Keratin
Insulin
(iv) Haemoglobin
...
Myosin
denaturation of protein
(b)
specificity of an enzyme
...
Explain why?
[Hint : In acidic solution, COO– group of zwitter ion formed from -amino
acid is protonated and NH3+ groups is left unchanged while in basic solution
deprotonation converts NH3+ to NH2 and COO– is left unchanged
...
Name the disease caused by deficiency of vitamin D
...
(i)
Why cannot vitamin C be stored in our body?
Define the terms hypervitaminosis and avitaminosis
...
Explain what is meant by :
(i)
a peptide linkage
(ii)
a glycosidic linkage?
[Hint : (i) Peptide linkage refers to the –CONH– linkage formed by reaction
between –COOH group of one amino acid with –NH2 group of the other
amino acid
...
]
19
...
20
...
SA(II) TYPE QUESTIONS (3-Mark Questions)
1
...
How
(i)
(ii)
(iii)
are carbohydrate classified?
Name four bases present in DNA
...
Give the structure of a nucleotide of DNA
...
Differentiate between the following :
(i)
secondary and tertiary structure of protein
...
(iii) fibrous and globular proteins
...
(i)
Deficiency of which vitamin causes right-blindness?
(ii)
Name the heterocyclic nitrogeneous base that is found in RNA only
...
What does it suggests
aboout the structure of glucose?
VALUE BASED QUESTIONS (4-Mark Questions)
1
...
She felt lethargic and did not have energy to do work
...
(a)
Name the vitamins whose deficiency will cause pernicious anemia
...
(d)
Mention the values shown by Neeta
...
(i)
Give one example each of fibrous protection and globular protein
...
192
1+1+1+2
[Class XII : Chemistry]
Unit - 15
POLYMERS
Points to Remember
1
...
2
...
Polythene, teflon, orlon etc
...
3
...
This
type of polymerisation proceeds through the elimination of certain simple
molecules such as H2O, NH3, HCl etc
...
Formaldehyde reacts with phenol and melamine to form the corresponding
condensation polymer products
...
5
...
6
...
A copolymer like Buna-S contains multiple units of 1, 3-butadiene
and styrene
...
Natural rubber is cis-1,4-polyisoprene
...
8
...
9
...
193
[Class XII : Chemistry]
10
...
Some substances like dimethyl phthalates, tripenylphosphate,
camphor etc
...
1-Mark Questions
1
...
2
...
3
...
4
...
5
...
Why?
6
...
What is the repeating structural unit in polythene polymer?
8
...
9
...
Write the structure of the momomeric unit of nylon-6
...
What is meant by copolymerisation?
12
...
13
...
14
...
2-Mark Questions
16
...
(i)
Nylon-6, 6
(ii)
PVC
17
...
18
...
19
...
20
...
194
[Class XII : Chemistry]
21
...
22
...
nylon-6, 6 buna-S, polythene
nylon-6, neoprene, polyvinylchloride
Write the structures of repeating units of
(i)
(ii)
(iii)
24
...
Define thermoplastic and thermosetting polymers
...
27
...
3-Mark Questions
28
...
(i)
Neoprene and
(ii)
Glyptal
Which one of the two is a condensation polymer?
29
...
Nylon-6
(ii)
Nylon-6, 6
Polythene
Write chemical equations for the synthesis of
(i)
Terylene
(iii)
(ii)
Teflon
195
Neoprene
[Class XII : Chemistry]
31
...
(i)
(iii)
32
...
Classify
the following into addition and condensation polymers
...
Polythene
PTFE
Polybutadiene
(iv) Bakelite
Write (a) name of monomers, (b) structures of the following polymers
...
Differentiate between thermoplastic and thermosetting polymers
...
35
...
36
...
37
...
addition polymers
(ii)
condensation polymers
Copolymers
(i)
What does designation 6, 6 in nylon 6, 6 polymer mean?
(ii)
Which polymers is obtained when free radical polymerisation of
chloroprene occurs? Write the structure of the polymers thus obtained
...
Write the structure of the monomer of each of the following polymers:
(i)
Nylon-6
(iii)
(ii)
Neoprene
196
Teflon
[Class XII : Chemistry]
40
...
41
...
Buna-S
(ii)
Nylon 6, 6
Write the names and structures of the monomers and the following polymers:
(i)
Polystyrene
(iii)
43
...
To make the awareness more impactful, they organized rally by joining hands
with other schools and distributed paper bags to vegetable vendors,
shopkeepers and departmental stores
...
After reading the above passage, answer the following questions:
1
...
What are biodegradable polymers? Give one example
...
Is polythene a condensation or an addition polymer?
4
...
How are following polymers are obtained? Write the names of monomers
and the structures of the respective polymers
...
A drug is a chemical agent which affects human metabolism and provides
cure from ailment
...
2
...
3
...
These are called
target molecules
...
Drugs are designed to interact with specific targets so that these have the
least chance of affecting other targets
...
5
...
6
...
These contain a mixture
of synthetic estrogen and progesterone derivatives
...
Chemicals are added to food for preservation, enhancing their appeal and
adding nutritive value in them
...
Artificial sweetening agents like aspartame, saccharin etc
...
9
...
10
...
11
...
12
...
198
[Class XII : Chemistry]
13
...
For example :
(i)
BHT (Butylated hydroxytoluene)
(ii)
BHA (Butylated hydroxyanisole)
14
...
15
...
VSA QUESTIONS (1-Mark Questions)
1
...
2
...
3
...
Why is sodium benzoate added to packed containers of jams and pickles?
5
...
6
...
With reference to which classification has the statement ‘ranitidine is an
antacid’ been given?
[Hint : Classification based on pharmacological effect
...
Give the name of medicine used for the treatment of syphilis
...
9
...
10
...
]
11
...
199
[Class XII : Chemistry]
[Hint : Chloroxylenol and Terpineol]
...
What precaution should be taken before administrating penicillin to a patient?
[Hint : To confirm beforehand that the patient is not allergic to penicilin
...
Explain why aspirin finds use in prevention of heart attacks?
[Hint : Due to anti blood clotting activity
...
Mention one use of drug meprobamate
...
]
15
...
16
...
]
*17
...
: Cimetidine or ranitidine prevents the interaction of histamines with
the receptors present in stomach wall and therefore, secretion of acid is
prevented]
...
While antacids and antiallergic drugs interfere with the function of
histamines, why do these not interfere with the function of each other?
[Hint
...
Therefore, they do not interfere with the function of each other)
...
Which of the following two compounds can be used as a surface agent
and why?
[Hint : Compound (i) acts as a surface agent because its one end is
hydrophobic while the other end is hydrophillic in nature
...
What type of drug is chloramphenicol?
21
...
22
...
23
...
200
[Class XII : Chemistry]
24
...
25
...
Give one example
...
What is the cause of a feeling of depression in human beings? Name a
drug which can be useful in treating depression
...
State an example and function of wide spectrum antibiotics
...
Hair shampoos belong to which class of synthetic detergent?
29
...
What is their chemical nature?
SA (I) TYPE QUESTIONS (2-Mark Questions)
1
...
Give two examples
...
What are narcotic and non-narcotic analgesics? Give one example of each
...
Explain the following terms as used in medicinal chemistry :
(i)
4
...
Give one important use of each of following :
(i)
Equanil
(ii)
Morphine
5
...
Give two examples
...
(i)
What are antibiotics?
(ii)
What is meant by the term broad spectrum antibiotic?
7
...
Choose the drug used fors
(i)
treating allergic conditions
(ii)
to get relief from pain
8
...
9
...
Give one example of each
...
What are antifertility drugs? Name the constituents of an oral contraceptive
...
What do you mean by non-biodegradable detergents? How can we make
biodegradable detergent like PHBV?
*12
...
What is the advantage of using antihistamines over antacids in the treatment
of acidity?
14
...
15
...
SA (II) Type Questions (3 - Mark Questions)
1
...
(iii)
2
...
Give suitable reason
...
(ii)
Chloroxylenol, phenol, chloamphenicol, bithional
...
[Hint :
(i)
(ii)
Chloramphenicol is a broad spectrum antibiotic
...
(iii)
3
...
Sodium benzoate is a food preservative
...
]
Give the main functions of following in the body of human beings
...
enzymes
neurotransmitter
Identify the class of drug :
(i)
chloramphenicol
(ii)
aspirin
(iii)
cimetidine or ranitidine
202
[Class XII : Chemistry]
5
...
analgesics
antifertility drugs
Give the name of medicine used in the treatment of following diseases:
(i)
(ii)
joint pain (in Arthritis)
(iii)
7
...
How are antiseptics different from disinfectants? How does an antibiotic
different from these two? Give one example of each of them
...
Explain the following terms with suitable examples :
(i)
cationic detergents
(ii)
anionic detergents
(iii)
nonionic detergents
*10
...
(ii)
cationic detergent
...
*11
...
[Hint : An enzyme inhibitor either blocks the active site of enzyme or
changes the shape of the active site by binding at an allosteric site
...
(i)
(ii)
Non-competitive enzyme inhibitor binds at allosteric site and changes
the shape of the active site in such a way that the substrate can not
recognise it
...
Competitive enzyme inhibitor competes with natural substance for
their attachment on the active sites of enzymes
...
2% phenol, or 1% phenol
13
...
VALUE BASED QUESTION (4-Marks Question)
1
...
Naresh works in a multi-national company
...
Mr
...
Mr
...
With regular Yoga
sessions Mr
...
After reading the above passage answer the following questions:
(i)
Write the values shown by Mr
...
(ii)
Which class of drugs is used in sleeping pills?
(iii)
Why is it not advisable to take sleeping pills without consultation with
the doctor?
(iv)
Given an example of sleeping pills used commonly
...
(a)
Discuss two ways in which drugs prevent the attachment of natural
substrate on active site of an enzyme
...
Classify the following into bactericidal and
bacteriostatic antibiotics:
Tetracycline, Penicillin, ofloxacin and chloramphenicol
...
(ii)
Question numbers 1 to 5 are very short answer questions and carry 1
mark each
...
(iv) Question numbers 11 to 22 are short answer questions and carry 3
marks each
...
(vi) Question numbers 24 to 26 are long answer questions and carry 5 markseach
...
Use of calculator is not permitted
...
Name the non-stoichiometric point defect responsile for colour in alkali
metala halides
...
What is the sign of H and S when a gas is absored by an adsorbent?
1
3
...
Write the structure of 3–Oxopentanal
...
Name the expected products of hydrolysis of sucrose
...
Differentiate between molarity and molarity for a solution
...
A chemical reaction is of first order w
...
t
...
r
...
reactant B
...
(b)
the concentration of A as well as B are doubled?
206
2
[Class XII : Chemistry]
8
...
I2 + Conc
...
MnO (aq) + C2O2 (aq) + H+ (aq)
4
4
2
Cr2O7 (aq) + Fe2+ (aq) + H+ (aq)
Which one of the following pairs of sustances undergoes SN2 substitution
reaction faster and why?
(a)
CH2Cl or
(b)
11
...
Radius of the
atom in the metal is 125 pm
...
Calculate the freezing point of an aqueous solution containing 10
...
86 K kg mol–1)
...
The rate of a reaction becomes four times when the temperature changes
from 300K to 320K
...
(R=8
...
Explain what is obsereved when
(a)
(b)
a beam of light is passed through a sol?
(c)
15
...
(c)
16
...
3
Assign reasons for the following:
(a)
(b)
Scadium (z=21) does not exhibit variable oxidation states and yet it
is regarded as transition element
...
The enthalpies of atomisation of transition elements are high
...
3
Complete the following chemical equations
...
How will you bring about following conversions? Write complete equations
in each case
...
Ethanal to 3–hydroxybutanal
Propanone to propene
3
Give the structures of A, B and C in the following reactions :
H O/H
CuCN
(i) NH , B
(a)
3
2
C6H5N2 Cl A B C
(ii)
(b)
NaNO2 / HCl
(i) Sn/HCl
C6H5NO2 A B
–
(ii) OH
273K
H O / H
2
C
20
...
HI
(b)
Br2 water
(c)
HNO3
Buna-S
(b)
Neoprene
(c)
Nylon–6, 6
3
Pick out the odd one amongst the following on the basis of their medicinal
properties
...
(a)
Luminal, seconal, terfenadine, equanil
(b)
Chloroxylenol, phenol, chloramphenicol, bithional
(c)
23
...
3
Sucralose, aspartame, alitame, sodium benzoate
3
Ravi a student of Class XII Chemistry wants to test the quality of water
samples in his locality
...
His friend Mohit suggested him to compare the hardness of water by
titrating it with Na4EDTA
...
209
[Class XII : Chemistry]
(a)
(b)
What is its denticity?
(c)
Mention the type of titration involved in the estimation of hardness
of watre
...
(b)
24
...
Calculate the emf of the following cell at 25°C :
4
Cu (s) | Cu2+ (10–1M) || Ag+ (10–3M) | Ag
[Given E = 0
...
How is the overall reaction represented?
(b)
Calculate the degree of dissociation of acetic acid at 298K, given that
m (CH3COOH) = 11
...
9 S cm2mol–1
0
m (H+)
25
...
1 S cm2mol–1
5
Explain each of the following :
(i)
(ii)
The electron gain enthalpy with negative sign for oxygen (–141
KJ mol–1) is numerically less than that for sulphur (–200 KJ
mol–1)
...
Florine does not exhibit any positive oxidation state
...
What is the basicity of H3PO3 and why?
Nitrogen is much less reactive than phosphorus at room
temperature
...
(c)
Write Kolbe’s reaction with an example
...
(i)
(ii)
(b)
Ethoxybenzene
2–Methyl–2–methoxypropane
...
(ii)
Phenol is a stronger acid than an alcohol
...
211
5
[Class XII : Chemistry]
ANSWERS
1
...
H 0
½
S 0
½
3
...
CH3
CH2
C
CH2
O
C
H
1
O
5
...
Molarity is defined as the number of moles of solute dissolved in 1L of
solution while molarity is the number of moles of solute dissolved in 1 kg
of 1000g of solvent
...
1
7
...
(ii)
1
In case when the concentration A and B both get doubled
(Rate)2 = K [2A] [2B]2
(Rate)2 = 2×2×2× K [A] [B]2 = 8 × Rate
Rate becomes 8 times
...
1
(a)
I2 + 10HNO3 (Conc
...
(i)
Acidified K2Cr2O7 oxidises iron(II) salt to iron (III)
2
Cr2O7 + 14H+ + 6Fe2+ 2Cr3+ + 6Fe3+ + 7H2O
(ii)
1
In neutral aqueous medium, thiosulphate is oxidised to sulphate
2
8MnO 3S2O3 H2O 8MnO2 6SO2 2OH
4
4
1
OR
(i)
1
(ii)
10
...
(a)
[½+½]
(b)
11
...
[½+½]
(i)
For ccp, edge length of the unit cell
a
4r
2
2 2r
½
a = 2 × 1
...
254 × 1022 unit cells
12
...
5 g, w1 = 200 g mol–1
M2 (MgBr2) = 24 + 80 × 2 = 184 g mol–1
Kf = 1
...
86 K kg mol1 10
...
592 K
13
...
314 J K–1 mol–1
k
Ea T2 T1
log 2
2
...
303 8
...
15 300 320
Ea = 55
...
1
The colloidal particles move towards oppositely charged electrodes
i
...
electrophoresis takes places
...
e
...
1
(c)
15
...
1
(a)
Impure nickel reacts with stream of CO and form volatile tetracarbonyl
nickel (o) which on further heating gives pure nickel
...
SiO2 + FeO FeSiO3
Flux
Gangue
1
Slag
OR
(a)
Preparation of pure alumina (Al 2 O 3 ) from bauxite involves
leaching process
...
Precipitate is filtered, washed, dried and heated to give pure Al2O3
...
xH2 O(s) Al2 O3 (s) xH2 O(g)
Alumina
870K
ZrI4
2075K
1
(b)
Zr + 2I2
Impure
Zirconium
Zr + 2I2
Pure
Zirconium
(c)
4 Au(s) + 8 CN– + 2H2O + O2 4[Au(CN)2]– + 4OH–
2[Au(CN)2]– + Zn 2Au + [Zn(CN)4]2–
16
...
Covalent bonding is
due to d-d overlapping
...
e
...
1
(c)
This is due to poorer shielding by 5f electrons in actinoids than that
by 4f-electrons in the lanthanoids
...
(i)
+ HI
215
1
[Class XII : Chemistry]
(ii)
(iii)
H
Br
+ HBr
H
H
H
H
CH3CH2CH = CH2 + HBr
H
CH3CH2CH
1
H
CH3
1
Br
18
...
NaoH
2 CH3CHO
CH3CH
CH2CHO
1
OH
CHO
O
COCl
COOH
C
HNO3
(ii)
SOCl2
C6H6
Anhy
...
H2SO4
CH3CH
CH2
OH
1
+
N2Cl
–
COOH
CN
+
CuCN
19
...
(a)
1
(B)
(C)
+
N2Cl
NH2
(i) Sn/HCl
–
(ii) OH
(b)
NH3
H2O/H
(a)
CONH2
–
OH
+
H2O/H
NaNO2/HCl
273-278K
1
Reaction with HI
CHO
(CHOH)4
RedP/HI
373K
CH3CH2CH2CH2CH2CH3
n-hexane
1
CH2OH
216
[Class XII : Chemistry]
(b)
Reaction with Bromine water
CHO
COOH
+ [O]
Br2water
(CHOH)4
(CHOH)4
CH2OH
Glucose
(c)
CH2OH
Glucose Acid
Reaction with HNO3
CHO
COOH
(CHOH)4
HNO3
Oxidation
(CHOH)4
CH2OH
Glucose
21
...
Terfenadine is antihistamine, other three are used as tranaquilizers
...
1
(c)
23
...
1
(a)
Ethylenediaminetetraacetate ion
1
(b)
6
1
(c)
Complexometric titration
1
(d)
Scientific attitude, work for community, help for others [Any one] 1
217
[Class XII : Chemistry]
24
(a)
Lead storage battery is a secondary battery
...
059
log
=
2
n
Ag
0
...
059V
0
...
0012
E
cell
1
1
Ecell = 0
...
9 + 349
...
7 S cm2 mol1
1
390 S cm2 mol1
3 10 2
25
...
It is due to
the fact that the axial bond pairs suffer more repulsion as
compared to equatorial abond pairs
...
1
(ii)
Due to smaller size or compact nature of 2p orbitals of oxygen,
electronic repulsion is more in oxygen than in sulphur, hence
oxygen has less negative electron gain enthalpy than sulphur
...
State
...
) 5NaCl + NaClO3 + 3H2O
(ii)
(a)
2Fe3+ + SO2 + 2H2O 2Fe2+ + SO2 + 4H+
4
2
O
(b)
(i)
H
P
OH
OH
Two, as the structure of H3PO3 has two P–OH bonds
...
4 KJ Mol-1) is much stronger than P-P single bond (bond
dissociation enthalpy of P-P bond 213 KJ Mol -1), therefore
nitrogen is much less reactive than phosphorus
...
+ H2O
+
C
C
...
+ H2O
...
+ H2O
...
OH
...
Noble gases being monoatomic gases have no interatomic
forces except weak dispersion forces, therefore they have low
boiling point
...
O
R
(ii)
C
CH3
H
O
H
O
R
H
R
1
C6H5OH C6H5O– + H+
ROH RO– + H+
Phenol gives H+ ion easily because it forms phenoxide ion
which is resonance stablized while alcohols does not provide
H+ ion readily, because alkoxide ion (RO–) is not stablised by
resonance, so phenol is more acidic than alcohols
...
It
stabilises the phenoxide ion by dispersing negative charge
...
Thus, o-nitrophenol is more acidic than
o-methoxyphenol
...
(ii)
Question numbers 1 to 5 are very short answer questions and carry 1
mark each
...
(iv) Question numbers 11 to 22 are short answer questions and carry 3
marks each
...
(vi) Question numbers 24 to 26 are long answer questions and carry 5 markseach
...
Use of calculator is not allowed
...
Give one example each of lyophobic sol and lyophilic sol
...
Write the IUPAC name of the compound
...
What type of intermolecular attractive interaction exists in the pair of
methanol and acetone?
1
4
...
Arrange the following in increasing order of basic strength :
1
C6H5NH2, C6H5NHCH3, C6H5N(CH3)2
6
...
)
222
[Class XII : Chemistry]
OR
Arrange the following in the order of property indicated against each set :
(i)
HF, HCl, HBr, HI – increasing bond dissociation enthalpy
...
2
7
...
2
8
...
State Raoult’s law for the solution containing volatile components
...
Explain the following terms :
2
(i)
(ii)
11
...
Write the equation involved in Reimer-Teiemann reaction
...
XeF4
(ii)
3
N2O5
Write the structural difference between while phosphorus and red
phosphorus
...
)
14
...
Give two examples of macromolecules that are chosen as drug
targets
...
(i)
Deficiency of which vitamin causes scurvy?
(ii)
What type of linkage is responsible for the formation of proteins?
(iii)
Write the product formed when glucose is treated with HI
...
(b)
Write an important characteristic of lyophilic sols
...
(i)
(iii)
17
...
(ii)
16
...
(iii)
...
Sulphur in vapour state exhibits paramagnetic behavour
...
3
The following data were obtained during the first order thermal
decomposition of SO2Cl2 at a constant volume:
3
SO2Cl2 (g) SO2 (g) + Cl2 (g)
Experiment
Time/s
Total pressure/atm
1
0
0
...
7
Calculate the rate of constant
...
6021, log2 = 0
...
Compare the following complexes with respect to shape and magnetic
behaviour
3
(i)
(ii)
20
...
(iii)
20
...
The two O-O bond lengths in the ozone molecule are equal
...
(ii)
23
...
What type of stoichiometric defect is shown by the crystal?
Calculate the mass of compound (molar mass=256 g mol–1) to be
dissolved in 75 g of benzene to lower its freezing point by 0
...
12 K kg mol–1)
...
To make the awareness more impactful, they organized
rally by joining hands with other schools and distributed paper bags to
vegetable vendors, shopskeepers and departmental stores
...
After reading the above passage, answer the following questions :
(i)
What values are shown by the students?
225
[Class XII : Chemistry]
(ii)
(iii)
Is polythene a condensation or an addition polymer?
(iv)
24
...
Is polythene a thermoplastic or thermosetting polymer?
(a)
Define the following terms :
(i)
(b)
Limiting molar conductivity
(ii)
4
Fuel cll
R esi ance of a conduct vi y cel f led w i h 0
...
If the resistance of the same cell when filled with 0
...
02 mol L–1 KCl solution
...
1 M KCl solution is 1
...
OR
(a)
State Faraday’s first law of electrolysis
...
(b)
Calculate emf of the following cell at 298 K :
Mg (s) | Mg2+ (0
...
01) | Cu(s)
[Given E0 =+2
...
(a)
How do you prepare :
(i)
K2MnO4 from MnO2 ?
(ii)
(b)
5
Na2Cr2O7 from Na2CrO4 ?
Account for the following :
(i)
Mn2+ is more stable than Fe2+ towards oxidation to +3 state
...
(iii)
Actinoid elements show wide range of oxidation states
...
Why does it shows so?
226
[Class XII : Chemistry]
(ii)
Which transition metal of 3d series has positive E°(M2+/M) value
and why?
(iii)
Out of Cr3+ and Mn3+, which is a stronger oxidizing agent and why?
(iv)
Name a member of the lanthanoid series which is well known to
exhibit +2 oxidation state
...
5
Write the products of the following reactions :
+
H
(i)
O + H2N – OH
(ii)
2C6H5CHO + conc
...
Carboxylic acid is a stronger acid than phenol
...
(i)
Wolif-Kishner reduction
(ii)
Aldol condensation
(iii)
Cannizzaro reaction
227
5
[Class XII : Chemistry]
MARKING SCHEME-2
1
...
½
Lyophobic Sol : Metal Sol, metal sulphides/hydroxides (or any other, any
one example in each case)
½
2
...
Hydrogen bonding
1
4
...
C6H5NH2 < C6H5 NHCH3 < C6H5N (CH3)2
6
...
1
(ii)
7
...
1
(or any other difference)
8
...
1
(ii)
9
...
1
For the solution containing volatile components, the partial vapour pressure
of each component is directly proportional to its mole fraction
...
1
228
[Class XII : Chemistry]
10
...
Half-life period of the reaction is the time in which the
concentration of the reactant is reduced to half of its initial concentration
...
(a)
HBr H+ + Br–
H
|+
CH3 – CH2 – O – H + H CH3 – CH2 – O – H
+
H
|+
+
CH3 – CH2 – O – H CH3 – CH2 + H2 O
CH3 – CH2
(b)
Br
+
–
CH3 – CH2 – Br
+
Br – CH2 + H2O
Br + CH2 – OH2
|
|
(Where R = –CH3)
R
R
OH
ONa
OH
|
| CHO
| CHO
|
|
+
CHCl3 + aq NaOH
H
salicylaldehyde
Xe
|
|
F
O
F
(ii)
F
O
|| N – O – N
||
(b)
(i)
O
(a)
|
12
...
White phosphorus
It exists in the form of polymeric
chain
...
Because in vapour form sulphur (S2) contains unpaired electrons in
* antiboding orbitals like O2 molecule
...
1
(iii)
15
...
½+½
Example : 1% phenol, SO2, Cl2 (or any other)
...
In anionic detergents, the anionic part of the molecule
is involved idn the cleansing action
...
1
(b)
Peptide linkage
1
(c)
17
...
(or any other)
½, ½
or log(x/m) = logK +1/n log p
230
1
[Class XII : Chemistry]
SO2Cl2 SO2 + Cl2
18
...
4 atm 0 atm 0 atm
At t = 100s (0
...
4 – x + x + x
Pt = 0
...
7 = 0
...
3
k
k
2
...
4
log
t
0
...
7
k
2
...
4
log
100
0
...
303
x 0
...
39 x 102 s1
100
1
(a)
1
[Ni(CN)4]2–
Ni28 [Ar]18 4s2 3d8
Ni(II) [Ar]18 3d8
1
1
1
1
1
1
1
1
4p
4s
3
sp hybridization
(Square Plannar)
(Diamegnetic)
1+½
[NiCl4]2–
Ni28 [Ar]18 4s2 3d8
Ni (II) [Ar]18 3d8
1
1
1
(b)
1
1
19
...
303
pi
log
t
2pt – pt
1
1
1
4s
3
4p
sp hybridization,
tetrahedral
(paramagnetic)
231
1+½
[Class XII : Chemistry]
20
...
1
(iii)
1
(i)
Schottky defect
1
(ii)
21
...
Decreases
1
(iii) Alkali metal halides/Ionic substances having almost similar size of
cations and anions (NaCl/KCl)
1
22
...
48K 5
...
48 75 256
5
...
8g
23
...
(atleast two values)
1
(ii)
Polymers which can be degraded by the action of microorganisms
...
g
...
1
(iii)
Addition polymer
...
1
232
[Class XII : Chemistry]
24
...
1
(b)
Cell constant = conductivity × resistance
= 1
...
29 cm–1
Conductivity of 0
...
248 S m–1 = 0
...
02 mol L–1
= 1000 × 0
...
(aq
...
059
[Mg2 ]
log
E cell = E° cell –
n
[Cu2 ]
1
E cell = 2
...
059V
0
...
01
½
E cell = 2
...
059V
log10
2
½
= 2
...
0295V = 2
...
1
(b) (i) Because of 3d5 (half filled) stable configuration of Mn2+
1
(ii) Because in zinc there is no unpaired electron/there is no contribution
from the inner d electrons
...
1
OR
(i) Mn, because of presence of 5 unpaired electrons in 3d subshell
½+½
(ii)
Enthalpy of reaction : Cu(s) Cu2+ + 2e– is highly endothermic,
which cann’t be outweighed by the factor (TS) at 298 K
...
rG
= – n F (Ecu / Cu2+)
= – n F (– Ecu / Cu2+/Cu)
Hence, E Cu2+/Cu is positive
(iii)
(iv)
Eu2+
(v)
MnO4– + 8H+ + 5e–
(iii)
+ 4H2O
N
...
Mn3+, because Mn2+ is more stable due to its half filled (3d5)
configuration
½+½
Cl – CH2 – COOH
COONa
1
1
(b) (i) Add NaHCO3, benzoic acid will give brisk effervescence whereas
benzaldeyde will not give this test, (or any other test)
1
(ii) Add Tollens’ reagent, propanal will give silver mirror whereas
propanone will not respond to this test
...
1
(ii) Because carboxylate ion (conjugate base) is more resonance
stabilized than phenoxide ion
...
NaOH
NNH2
KOH / Ethylene glycol
Heat
O +
C
O + Conc
...
(ii)
Question numbers 1 to 5 are very short answer questions and carry 1
mark each
...
(iv) Question numbers 11 to 22 are short answer questions and carry 3
marks each
...
(vi) Question numbers 24 to 26 are long answer questions and carry 5 markseach
...
Use of calculator is not permitted
...
A and B liquids on mixing produce a warm solution
...
Why is ferric chlorice preferred over potassium chloride in case of a cut
leading to bleeding?
3
...
Why is ortho-nitrophenol more acidic than ortho-methoxyphenol?
5
...
6
...
144nm) crystallizes in a face
centered unit cell
...
[NA=6
...
7
...
Give reason
...
(b)
Si doped with P, a group 15 element
...
Complete the following reactions :—
(a)
P4 8SOCl 2
(b)
2 I O2 H2 O
9
...
(Atomic number of Co is 27)
...
(a)
Write the structure of following compound
...
11
...
(a)
(b)
12
...
In a hydrolysis reaction, 5g ethyl acetate is hydrolysed in presence of dilute
HCl in 300 minutes
...
14
...
(b)
15
...
(b)
Write the structures of the monomers of dacron
...
Nylon-6, Buna-S, Polythene
...
Give one example for each of the following :
(a)
(b)
A non-ionic detergent
...
An artificial sweetener whose use is limited to cold drinks
...
(a)
Give chemical tests to distinguish between the following compounds
(One test in each case)
...
Give the structures of A, B and C and
write the reactions involved
...
(a)
Give the mechanism of the following reaction :
dil H SO
2
4
CH3 CH2 OH CH2 CH2 H2 O
443K
(b)
19
...
Give reasons—
(a)
(b)
PCl5 is known but NCl5 is not known
...
Interhalogen compounds are more reactive than halogens except F2
...
(a)
Give one main difference between lyophillic and lyophobic colloids
...
(ii)
Electric current is passed through a colloidal solution
...
Determine the molarity of an antifreeze solution containing 250g water
mixed with 222g ethylene glycol (C2H6O2) (molar mass 62 g mol –1) The
density of this solution is 1
...
22
...
(i)
(ii)
(c)
23
...
In the upper part of blast furnace (Lower temperature)
Why can’t aluminium be reduced by carbon?
A car driver was stopped by the policeman and asked to breath in an
electronic device which contained some chemical
...
(c)
Write the chemistry involved in this test
...
Why was car driver stopped and asked to breath in the electronic
device?
Mention the values of such tests
...
A steady current of
2
...
078g of silver was deposited
...
8 g mol-1, F = 96,500 Cmol–1]
...
OR
(a)
What is a fuel cell? What is its main advantage?
239
[Class XII : Chemistry]
(b)
What are the reactions occurring at the cathode and anode of
a Leclanche cell?
(c)
In the button cell, widely used for watches and other devices, the
following reaction takes place :
Zn(s) Ag2O(s) H2O(l) Zn2 (aq) 2Ag(s) 2OH– (aq)
Give the cell representation and determine the value of Kc for the above
reaction using the following data
...
344V)
Zn2 (aq) 2e Zn(s)
(E° = –0
...
Explain the following :
(a)
Actinoids show large number of oxidation states
...
(c)
Chromium is a typical hard metal while mercury is a liquid
...
(e)
Silver is a transition metal but zinc is not
...
(b)
Complete the following reactions :
(i)
(ii)
(c)
8MnO4– + 3S2O32– + H2O
Cr2O72– + 3Sn2+ + H+
Which of the following has maximum number of unpaired electrons?
Ti3+, V3+, Fe2+, Mn2+
(d)
Based on the following data, arrange Fe2+, Mn2+ and Cr2+ in the
increasing order of stability of +2 oxidation state
240
[Class XII : Chemistry]
E°(Cr3+/Cr2+)= –0
...
5V, E°(Fe3+/Fe2+)= 0
...
(a)
Identify A, B and C in the following reaction :
dil H SO
dil NaOH
heat
2
4
CH CH A B C
HgSO
4
(b)
Give reasons
(i)
p-Nitrobenzoic acid has higher Ka value than benzoic acid
...
OR
(a)
An organic compound (A) has molecular formula (C5H10O)
...
4-DNP reagent
...
On oxidation under vigorous
conditions gives ethanoic acid and propanoic acid
...
Identity
(A), (B) and (C) and write the reactions involved
...
(i)
(A) (C3H6O) reacts with PhMgBr and is then hydrolysed
...
(iii)
(A) does not give connizzaro reaction
...
(ii)
Question numbers 1 to 5 are of 1 each
...
(iii) Question numbers 6 to 10 are of 2 marks each
...
(iv) Question numbers 11 to 22 are of 3 marks each
...
(v)
Question number is of 23 4 mark
...
(vi) Question numbers 24 to 26 are of 5 marks each
...
(vii) Use log table, if necessary
...
1
...
Which type of deviation
from Raoult’s law is shown by solution?
2
...
3
...
Write the IUPAC name of [Co(NH3)5(SO4)]Br
...
How will you distinguish between phenol and cyclohexanol by suitable
chemical test?
6
...
0 g of Glauber’s salt, Na2SO4
...
(Molar mass = 322g
mol-1) in 0
...
[Given Kf for water = 1
...
List two difrferences between order of reaction and molecularity of reaction
...
Outline the principle of refining of metals by the following methods:
(a)
Zone refining
(b)
Electrolytic refining
OR
How is copper extracted from copper pyrities? Write the equations of the
reactions involved
...
Account the following:
(a)
(b)
10
...
Schottky defect lowers the density of the crystal
...
KOH
A
Br 2
B
(i) Alc
...
The rate of a reaction quadruples when the termperature changes from
293K to 313K
...
(R = 8
...
12
...
(c)
13
...
A beam of light is passed through a colloidal solution
...
Cl2 NaOH Hot & conc
...
PHBV (Poly--hydroxybutyrate-CO-hydroxyvalerate) is biodegradable
polymer
...
(a)
How PHBV has found utility in medicines as capsule?
(b)
Is it an addition polymer or a condensation polymer?
(c)
Write the structure of PHBV
OR
Write the monomers of following polymers and mention one use of each
polymer
...
PAN
Glyptal
Give reasons for the following:
(a)
t-Butyl bromide has lower boiling point than n-butyl bromide
...
The dipole moment of chlorobenzene is lower than that of cyclohexyl
chloride
...
Give the pharmacological functions of the following type of drugs:
(a) Analgesics
18
...
(i)
HI
(ii) Acetic anhydride
(b
19
...
What are
reqpresented by the letter ‘D’ and sign (+)?
(a)
Give a chemical test to distinguish between the following pairs of
compounds:
NH2 and
CH2 NH2
244
[Class XII : Chemistry]
(b)
Illustrate the following with an example of reaction in each case:
(i)
(ii)
20
...
(a)
A 0
...
004 bar at 100°C
...
Explain why 4-nitrophenol is more acidic than 4-methoxyphenol?
Name the animal starch which is broken down by enzymes to glucose
when body needs it
...
(a)
XeF2
(b)
ClF3
(c)
Write the IUPAC name of the organic compound:
CH3
CH3CH2CH2
N
CH2CH3
23
...
They noticed that most of people of that
village were having swollen neck
...
(a)
(b)
Give a remedy of the problem
...
(d)
24
...
What value do you associate with it
...
Explain why galvanised iron does
not rust even if the coating of zinc is broken
...
96 V
...
[Given : R = 8
...
Why does
the conductivity of any electrolyte decreases with dilution?
(b)
Predict the products of electrolysis in each of the folloiwng:
(i)
An aqueous solution of AgNO3 with silver electrodes
...
(iii)
A dilute solution of H2SO4 with platinum electrodes
...
23V, E Ag / Ag 0
...
83V ]
25
...
Write chemical equations of ractions involved
...
(ii)
Transition metal ions in acqueous state are coloured
...
OR
(a)
Indicate the steps involved in the preparation of KMnO from pyrolusite
4
ore
...
(b)
account for the following:
(i)
K2Cr2O7 is preferred over Na 2Cr2O7 in volumetric analysis
though both are oxiding agents
...
The actinoids exhibits a greater range of oxidation states as
compared to lanthanoids
...
(a)
Write structural formulas and names of four possible aldol condensation products obtained from propanal and ethanal
...
(b)
Give reasons for the following:
(i)
Carboxylic acids do not give characteristic reactions of carbonyl
group
...
OR
(a)
Completye the following reaction statements by giving the missing
starting material, reagent or product as required::
(i)
(ii)
?
O3
Zn – H2O
O + HCHO
CH3 COCH2COOC 2H 5
(i) NaBH4
?
+
(ii) H3O
CH2OH
(iii)
(b)
KMnO4
?
KOH, heat
Write one chemical equation for each to illustrate the folloiwng
reactions:
(i)
Hell-Volhard-Zelinsky reaction
(ii)
Cannizzaro reaction
247
[Class XII : Chemistry]
Title: Chemistry Study Material
Description: Best Chemistry Study Material Issued by Central Board Of Secondary Education (CBSE) For Class 12th................I Hope This Material is useful for you.........Thank you...........& All the Best for your studies..
Description: Best Chemistry Study Material Issued by Central Board Of Secondary Education (CBSE) For Class 12th................I Hope This Material is useful for you.........Thank you...........& All the Best for your studies..