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CHEMISTRY A

OCR 2024
GCSE Chemistry A (Gateway Science)
J248/03 (Higher Tier)
With Marking Scheme Merged

Oxford Cambridge and RSA

Friday 17 May 2024 – Morning
GCSE (9–1) Chemistry A (Gateway Science)
J248/03 (Higher Tier)
Time allowed: 1 hour 45 minutes
You must have:
• a ruler (cm/mm)
• the Data Sheet for GCSE (9–1) Chemistry A
(inside this document)

H

You can use:
• a scientific or graphical calculator
• an HB pencil
2 *

*

J

2

4

8

2
Section A
You should spend a maximum of 30 minutes on this section
...


1

Which property is characteristic of a metal?
A It forms acidic oxides
...

C It is malleable
...


Your answer

2

[1]

Graphite and graphene are allotropes of carbon
...
B
Graphite has four bonds from each carbon atom, graphene only has three
...

D Graphite is made up of layers, graphene is a single layer
...

What is the formula of lithium phosphate?

A Li(PO4)3 B
Li2PO4 C
Li2(PO4)3 D
Li3PO4
Your answer

© OCR 2024

[1]

3
4

Which statement about a reducing agent is correct?
A It oxidises another species and is itself oxidised
...
C It
reduces another species and is itself oxidised
...

Your answer

5

[1]

Which statement about alkalis is correct?
+
A They form H ions in solution
...

C They react with metals to form a salt and hydrogen
...


Your answer
6

[1]

Which equipment is needed to set up an electrolysis experiment?
A A battery, a beaker, a funnel and wires
B A battery, a beaker, electrodes and wires
C A battery, crocodile clips, electrodes and a thermometer
D A beaker, electrodes, a funnel and a thermometer
Your answer

© OCR 2024

[1]

Turn over

4
7

Which products are formed in the electrolysis of sodium chloride solution?
Anode

Cathode

A

chlorine

hydrogen

B

chlorine

sodium

C

oxygen

hydrogen

D

oxygen

sodium

Your answer
8

[1]

How did Mendeleev group elements together to develop his Periodic
Table? A Based on chemical properties and left gaps
B Based on mass number and atomic number
C Based on physical properties and atomic number D
Based on physical properties and left gaps

Your answer
9

[1]

What is the mass of one atom of beryllium, Be?
Relative atomic mass (Ar): Be = 9
...

The Avogadro constant is 6
...
A 6
...
50 × 10
g
24
C 2
...
42 × 10 g
Your answer

© OCR 2024

[1]

5
10 Zinc reacts with iron chloride to form zinc chloride and iron
...

Which row of the table shows the reactions at the electrodes?

A
B
C
D

Cathode

Anode

3+
–
Al
+ 3e
Al
3+
–
Al
Al + 3e
3+
–
Al
+ 3e
Al
–
Al 3+ Al + 3e

–
O2 + 2e
2–
–
O + 2e
O 2
2–
–
2O
O 2 + 4e
2–
–
2O + 4e
O 2

O2–

Your answer

[1]

12 An element has the electronic configuration 2
...
4
...
Period 4 as it has 4 electrons in the outer shell
...
Period 4 as it has 4 electron shells
...
Period 3 as it has 3 electrons in the outer shell
...
Period 3 as it has 3 electron shells
...

2Cu(NO3)2

2CuO + 4NO2 + O2

How many moles of products are formed if 18 mol of copper nitrate decomposes?
CuO (mol)

NO2 (mol)

O2 (mol)

A

18

18

18

B

18

36

9

C

36

18

9

D

36

36

18

Your answer

[1]

14 Solutions can have different pH values
...
Which statement is correct?
A At 25 °C, bromine does not have enough heat energy to melt
...

C Bromine has a higher boiling point than fluorine and a higher melting point than iodine
...

Your answer

© OCR 2024

[1]

7
BLANK PAGE

PLEASE DO NOT WRITE ON THIS PAGE

© OCR 2024

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8
Section B
16
(a) A scientist investigates dissolving four different tablets in
water
...

3
They add each tablet to 20 cm of water and time how long it takes for the tablet to

dissolve
...

Surface area
of tablet
2
(cm )

Volume
of tablet
3
(cm )

Surface area
to volume

Time taken to
dissolve

ratio

(seconds)

A

2
...
3

9
...
5

0
...
5 : 1

27

C

1
...
2

D

3
...
2

Tablet

(i)

62
15
...


Surface area to volume ratio =
...

As the surface area to volume ratio
...
time to dissolve
...
Explain why the scientist is incorrect
...


...

[2]

© OCR 2024

9
(b) The scientist performs thin layer chromatography on solutions of each of the tablets
...

State what the scientist could use to see the spots
...
[1]

(ii) After the scientist uses a method to see the spots, the chromatogram for Tablet A is shown
...


Rf value =
...

Different separation methods are used depending on the mixture
...

Separation method

Crystallisation

Mixture
Insoluble solid
and liquid

Filtration

Solution containing a
soluble solid dissolved
in a liquid

Fractional
distillation

Three liquids with
different boiling points
[2]

(b) The student decides to use simple distillation to separate a mixture
...


Flask containing mixture
Collection flask
Bunsen burner

(i)

A liquid in the mixture is flammable
...


...
[1]

© OCR 2024

11
(ii) The student wants to record the boiling point of the pure liquid that is collected in the collection
flask
...


...
[1]

(c) The pure liquid collected has the molecular formula (C2H5)2O and a boiling point of 35
°C
...

The empirical formula is CH2
...

The pure liquid contains two compounds
...

The pure liquid will be a gas at above 35 °C
...

Relative atomic mass (Ar): C = 12
...
0 O = 16
...
[3]

© OCR 2024

Turn over

12
18 A scientist is studying two chemical reactions
...

(a) The reaction profile for the exothermic reaction is shown
...


...
[1]

(ii) Describe one difference and one similarity the scientist will see in the reaction profile for the
endothermic reaction
...


...


...

This is the balanced symbol equation for the reaction
...


H

H

H

H

C

C

C

H

H

H

H +5O

O

3O

C

O + 4

O
H

H

The table shows the bond energies
...


Energy transferred =
...

Use your answer to part (b)(i) to calculate the energy change for this reaction
...
kJ / mol [2]

© OCR 2024

Turn over

14
(c) A student studies a different reaction
...

(i)

Some possible steps for a method are given in the list
...

A

Add the solid to the solution
...


C

Cover the top of the reaction with cotton wool
...


E

Put the solution into a beaker and use a thermometer to record
the temperature before the reaction starts
...


G

Use a thermometer to record the temperature as the reaction progresses
...
26 25 24

23
Temperature
(°C)

22
21
20
19

18

0 50 100 150 200 250 300 350 400 Time (seconds)

The student concludes that the reaction is exothermic
...


...


...
[2]

© OCR 2024

Turn over

16
19 Many scientists were involved in the development of the atomic model
...

1
...

2
...

[2]
(b) Atoms are either oxidised or reduced to form ions
...

Atoms are
...
Atoms
...

Atoms are
...
Atoms
...

[2]

(ii) The table shows information about three different
ions
...

Number of
protons

Number of
neutrons

Number of
electrons

Mass number

2+
Mg

12


...


19

3

4

2


...

+
State one difference and one similarity between the Li ions formed from different isotopes
of lithium
...


...


...
2 cm wide
...
Use your knowledge of the typical radius of atoms in your calculation
...
[3]

(c) Ions are also formed when acids and alkalis dissolve in water
...

A dilute solution has a low ratio of acid to volume of solution
...

A strong acid can be made into a concentrated solution or a dilute solution
...

A weak acid can only be made into a dilute solution
...

Describe two things the student could do to make a solution with a lower pH
...



...



...

(i)

Complete the diagram to show what happens to the particles as a solid changes to a liquid
...

Boiling describes a gas turning into a liquid
...

Melting is a physical change
...

The arrangement of particles becomes more random during condensing
...

Explain two limitations of the particle model
...


...


...

The graphs show how the temperature changes as three different formulations, A, B and C,
are heated
...

Formulation
...


...


...


Diamond

Chlorine, Cl 2

Poly(ethene)

All the substances contain covalent bonds between the atoms
...

Use your knowledge of structure and bonding
...


...


...


...


...


...


...

Explain why ionic compounds can conduct electricity when dissolved in water, but not
when solid
...


...


...
[3]

(ii) Construct the dot and cross diagram for the ions in magnesium chloride, MgCl
2
...


Dot and cross diagram:

[2]

© OCR 2024

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22
22 A student is making a sample of magnesium carbonate, MgCO3
...

Method

Cost of starting
materials (£)

Mass of MgCO3
produced (g)

Is the MgCO3
pure?

1

12
...
24

yes

2

11
...
90

no

3

15
...
34

yes

4

20
...
86

no

(a) Which method should the student use to make their sample?
Explain your answer
...

Reason
...


...

[3]
(b) A teacher shows the student how to purify magnesium carbonate
...


...
[1]

(c) The student reacts the magnesium carbonate they have made with hydrochloric acid
...
Include state symbols
...
) + H2O(l) +
...
2 mol of hydrochloric acid in the reaction
...

At the end of the reaction, 0
...

Calculate the mass of magnesium carbonate that the student uses in the
reaction
...
0 Mg = 24
...
0

Mass of magnesium carbonate =
...
You must write the question numbers clearly
in the margin
...


...


...


...


...


...


...


...


...


...


...


...


...

© OCR 2024

25

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© OCR 2024

27

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OCR qualifications include
AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals, Functional Skills,
Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT,
business, languages, teaching/training, administration and secretarial skills
...
OCR is a not-for-profit organisation; any surplus made
is invested back into the establishment to help towards the development of qualifications and
support, which keep pace with the changing needs of today’s society
...
It shows the basis on which marks were awarded by examiners
...

All examiners are instructed that alternative correct answers and unexpected approaches
in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and
skills demonstrated
...

© OCR 2024

Oxford Cambridge and RSA Examinations

J248/03

Mark Scheme

June 2024

MARKING INSTRUCTIONS
PREPARATION FOR MARKING
RM ASSESSOR
1
...


2
...
These are available in RM Assessor
...


Log-in to RM Assessor and mark the required number of practice responses (“scripts”) and the required number of
standardisation responses
...


Mark strictly to the mark scheme
...


Marks awarded must relate directly to the marking criteria
...


The schedule of dates is very important
...
If you experience problems, you must contact your Team Leader (Supervisor) without delay
...


If you are in any doubt about applying the mark scheme, consult your Team Leader by telephone, email or via the RM Assessor
messaging system
...


Mark Scheme

June 2024

Crossed Out Responses
Where a candidate has crossed out a response and provided a clear alternative then the crossed out response is not marked
...

Rubric Error Responses – Optional Questions
Where candidates have a choice of question across a whole paper or a whole section and have provided more answers than required, then
all responses are marked and the highest mark allowable within the rubric is given
...
(The underlying assumption is that the candidate has penalised themselves
by attempting more questions than necessary in the time allowed
...

When a question requires candidates to select more than one option/multiple options, then local marking arrangements need to ensure
consistency of approach
...

Short Answer Questions (requiring only a list by way of a response, usually worth only one mark per response)
Where candidates are required to provide a set number of short answer responses then only the set number of responses should be marked
...
The remaining responses should not then be marked
...
(The underlying assumption is that the candidate
is attempting to hedge their bets and therefore getting undue benefit rather than engaging with the question and giving the most
relevant/correct responses
...
)
Longer Answer Questions (requiring a developed response)
Where candidates have provided two (or more) responses to a medium or high tariff question which only required a single (developed) response
and not crossed out the first response, then only the first response should be marked
...

6
...
If
the candidate has continued an answer there then add the annotation ‘SEEN’ to confirm that the work has been seen
...


Award No Response (NR) if:
•

there is nothing written in the answer space

Award Zero ‘0’ if:
• anything is written in the answer space and is not worthy of credit (this includes text and symbols)
...

8
...
Please refer to
these comments when checking your practice responses
...

If you have any questions or comments for your Team Leader, use the phone, the RM Assessor messaging system, or email
...


Assistant Examiners will send a brief report on the performance of candidates to their Team Leader (Supervisor) via email by the end of the
marking period
...
Constructive
criticism of the question paper/mark scheme is also appreciated
...


Mark Scheme

June 2024

For answers marked by levels of response:
Read through the whole answer from start to finish, using the Level descriptors to help you decide whether it is a strong or weak answer
...
Using a ‘best-fit’ approach based on the skills and science content evidenced within the
answer, first decide which set of level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer
...

The lower mark should be awarded where the level descriptor has been evidenced but aspects of the communication statement (in
italics) are missing
...

The communication statement determines the mark within a

level
...


Mark Scheme

Annotations available in RM Assessor

Annotation

Meaning
Correct response
Incorrect response
Omission mark
Benefit of doubt given
Contradiction
Rounding error
Error in number of significant figures
Error carried forward
Level 1
Level 2
Level 3
Benefit of doubt not given
Noted but no credit given
Ignore

6

June 2024

J248/03

12
...

Annotation

Meaning

/

alternative and acceptable answers for the same marking point



Separates marking points

DO NOT ALLOW

Answers which are not worthy of credit

IGNORE

Statements which are irrelevant

ALLOW

Answers that can be accepted

()

Words which are not essential to gain credit

__

Underlined words must be present in answer to score a mark

ECF

Error carried forward

AW

Alternative wording

ORA

Or reverse argument

7

June 2024

J248/03
13
...
This material includes:
•

the specification, especially the assessment objectives

•

the question paper

•

the mark scheme
...

You should ensure also that you are familiar with the administrative procedures related to the marking process
...
If you are examining for the first time, please read carefully Appendix 5 Introduction to Script Marking:
Notes for New Examiners
...
Your first point of contact is your Team Leader
...


AO1
...


AO1
...

Apply knowledge and understanding of scientific ideas and scientific enquiry, techniques and procedures
...
1

Apply knowledge and understanding of scientific ideas
...
2

Apply knowledge and understanding of scientific enquiry, techniques and procedures
...
1

Analyse information and ideas to interpret and evaluate, make judgements and draw conclusions and develop and improve
experimental procedures
...


AO3
...


AO3
...


AO3
...


AO3
...


AO3
...


AO3
...


AO3
...


AO3
...


9

J248/03

Mark Scheme

June 2024

For answers to Section A if an answer box is blank ALLOW correct indication of answer e
...
circled or underlined
...
1

2

D

1

1
...
1

4

C

1

1
...
1

6

B

1

1
...
2

8

A

1

1
...
1

10

B

1

2
...
2

12

D

1

1
...
1

14

C

1

2
...
1

Guidance

J248/03

Mark Scheme

Question
16 (a)

(i)

Answer
First check the answer on the answer line
If answer = 7
...
5 ÷ 0
...
5
0
...
2=1

(a)

(ii)

Marks
2

June 2024
AO
Guidance
element
2 x 2
...


✓

✓
ALLOW 15:2 for 1 mark

As the surface area to volume ratio increases/gets larger,
the tablet will take less time to dissolve

✓

1

3
...
1b No mark for no; marks are for explanation

✓

So it will take less / least time to dissolve /

ALLOW Tablet D does not have smallest surface

dissolves faster / fastest

area to volume ratio so will not dissolve slowest

✓

✓

Tablet C will dissolve slowest as has smallest
surface area to volume ratio

11

✓

J248/03

Mark Scheme

Question
(b)

(i)

Answer
(Use a) locating agent / stain / UV light

Marks

✓

1

June 2024
AO
Guidance
element
1
...
g
...
73 / 0
...
4÷6
...
73

1
...
2

✓
ALLOW ECF from incorrect distances
ALLOW 0
...
73

OR
distances moved = 4
...
0

✓

✓
Rf value = distance moved by spot /4
...
0
= 0
...
7 for 0
...
2 Any one correct = one mark
All three correct = two marks

3
...
3b

ALLOW use an (electric) heater / heating plate
ALLOW idea of clamping the (round bottom) flask
(to prevent it falling over)
ALLOW use a temperature probe
DO NOT ALLOW thermometer added to collection
flask / receiving flask

13

J248/03

Mark Scheme

Question

Answer

2

AO
element
2 x 2
...
2

Marks

(c)

June 2024
Guidance

The empirical formula is CH2
...

The pure liquid contains two compounds
...

✓
The pure liquid will be a gas at above 35 °C
...
0 / 74 award 3 marks
4 x 12
...
0 OR 2 x 12
...
0
10 x 1
...
0 OR 5 x 1
...
0
✓

IGNORE any units given

✓

✓

(48
...
0 + 16
...
0

ALLOW ECF for addition of incorrect numbers of
C, H and O if no other mark awarded

14

J248/03

Mark Scheme

Question

Answer

18 (a)

(i)

Products are lower (in energy) than reactants / ORA

(a)

(ii)

Difference
Idea of (energy of) reactants will be lower than (energy
of) products / ORA

1

AO
element
2
...
1

Marks
✓

June 2024

Similarity
There will still be an activation energy /
idea that energy will increase then decrease between
(b)

(i)

8 x 465 = 3720

(ii)

3

3 x 2
...
2

Energy change = Bonds broken – Bonds made /
= 6480 – 8514
= -2034

✓

ALLOW ECF from (b)(i)
ALLOW 8514 – 6480 = (+)2034 (kJ / mol) for 1
mark
AND ALLOW ECF from (b)(i)

✓

15

J248/03

Mark Scheme

Question
(c)

Answer

Marks

(i)

3
D

F

A

B

G

Step 1

Step 2

Step 3

Step 4

Step
5

D is step 1

June 2024
AO
element
3 x 3
...
1b

ALLOW a correct quoted temperature increase

✓
IGNORE idea that energy was lost from the
reactants / energy is lost to the surroundings
IGNORE idea that the solution has taken in energy
IGNORE ideas linked to bond breaking / making

16

J248/03

Mark Scheme

Question
19

(a)

Answer

Marks

Any two from:

2

June 2024
AO
element
2 x 1
...
Atoms lose
electrons to form positive ions
...
1

Atoms are reduced to form negative ions
...


Oxidised AND reduced for 1 mark
Lose AND gain for 1 mark
Mark independently

✓✓

(b) (ii)

2
Number
of
protons

Number of
neutrons

Number of
electrons

Mass
number

Mg2+

12

12

10

24

F-

9

10

10

19

3

4

2

7

Ion

Li

+

2 x 2
...
1

Guidance

IGNORE different (relative) atomic masses
+

idea that number of neutrons in “new” Li will not be 3 ✓
Similarity
Same number of protons / all have 3 protons /
same number of electrons /
same atomic number /
same charge / all have 1+ charge ✓
(b) (iv)

IGNORE idea that they have all lost 1 electron

First check the answer on the answer line
If answer = 2
...
1 nm ✓

1
...
2 cm = 0
...
2 x 10-2 m / 5
...
1

ALLOW conversion of atomic radius to same
units as Mg metal for this MP, e
...
, 1 x 10-8 cm

0
...
2 x 10-2 ÷ (2 x (1 x 10-10 )) = 2
...
2

ALLOW ECF for 5
...
6 x 1010

18

J248/03

Mark Scheme

Question
(c)

(i)

Answer

2

AO
element
2 x 1
...
3b

Marks

A dilute solution has a low ratio of acid to
volume of solution
...


A weak acid can only be made into a
dilute solution
...
1

Note: the particles do not need to fill the boxes

2

2 x 1
...
g
...


Freezing is a chemical change
...


The amount of energy needed to melt a substance
depends on the strength of the forces
✓
between particles
...


20

J248/03

Mark Scheme

Question

Answer

Marks

(a) (iii)

2

June 2024
AO
element
2 x 1
...
2a

MP2 is dependent on MP1

ALLOW idea that B has the highest temperature
before it changes state

21

J248/03
Question
21 (a)

Mark Scheme
Answer

Marks

Please refer to the marking instructions on page 4 of this
mark scheme for guidance on how to mark this question
...

There is a well-developed line of reasoning which is clear
and logically structured
...


June 2024
AO
Guidance
element
3 x 1
...
1 – Demonstrates knowledge and
3 x 2
...

• covalent bonds are very strong
• a lot of energy is required to break covalent
bonds
• intermolecular forces are weaker than covalent
bonds
• more energy is needed to break covalent bonds
than overcome intermolecular forces
• more atoms in a molecule mean more
intermolecular forces
• more intermolecular forces require more energy
to overcome
AO2
...

There is a line of reasoning presented with some
structure
...

Level 1 (1–2 marks)
Demonstrates limited knowledge and understanding of
the structure and bonding in some of the structures
OR
Attempts to apply knowledge and understanding to
explain why diamond has the highest melting point
...
The information is in the most part relevant
...


23

June 2024
AO
element

Guidance

J248/03

Mark Scheme

Question
(b)

(i)

Answer

Marks

Idea that ionic compounds contain ions ✓

3

Idea that the ions cannot move in a solid/ions are held in
fixed positions

✓

June 2024
AO
Guidance
element
3 x 1
...
2

DO NOT ALLOW structures with shared electrons
Two correct electronic structures but no charges
award one mark
Two correct charges with incorrect electronic
structure award one mark
The ionic charges must not be shown in the
nucleus

Correct magnesium ion / 2
...


i
...
,

ALLOW answers showing the transfer of electrons
providing the same electrons are not shown twice
All electrons can be dots or crosses
If dots and crosses are used the number of each
must be correct
Correct chloride ion / 2
...
8
OR correct chloride ion showing full outer shell only



Inner shell electrons do not need to be shown but
must be correct if they are shown
...
2b

✓

(Method 3) produces more MgCO3 than method 1

ALLOW idea of producing the highest mass of
MgCO3 whilst still being pure for 2 marks

✓

The cost per gram is less than method 1 (which also
produces pure MgCO3) ✓
(b)

Guidance

ALLOW 1 mark only if Method 1 is selected with
reason given that it is pure

Any one from:

1

3
...
g
...
2

Both species ✓
Both state symbols ✓
ALLOW MgCl2 (aq) / CO2 (g) for 1 mark if no other
mark awarded

25

J248/03

Mark Scheme

Question
(c) (ii)

Answer

Marks

First check the answer on the answer line
If answer = 9
...
2

Guidance

0
...
2 mol of HCl /
Idea of 1:2 mole ratio MgCO3 : HCl
Mr of MgCO3 = 84
...
1 x 84
...
43 g ✓

ALLOW ECF from incorrect Mr and/or moles of
MgCO3

Mass of MgCO3 used in the reaction = 8
...
82
= 9

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