2025 OCR GCSE (9–1) Combined Science A (Gateway Science) J250/10 Chemistry (Higher Tier)
Combined Question Paper & Final Marking Scheme
Oxford Cambridge and RSA
Friday 13 June 2025 – Morning
GCSE (9–1) Combined Science A
(Gateway Science)
J250/10 Chemistry (Higher Tier)
*1862816814*
Time allowed: 1 hour 10 minutes
You must have:
• a ruler (cm/mm)
• the Data Sheet for GCSE (9–1) Combined Science A
H
(Chemistry) (inside this document)
You can use:
• a scientific or graphical calculator
• an HB pencil
* J 2 5 0 1 0 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined pages at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 60.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 24 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/8687/2] OCR is an exempt Charity
DC (WW/CB) 351886/4 Turn over
, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 The equation shows a reaction that has reached dynamic equilibrium.
N2(g) + 3H2(g) 2NH3(g)
Which statement explains why this reaction is a dynamic equilibrium?
A N2 and H2 are gases.
B The rates of the forward and reverse reactions are equal.
C The reaction has stopped.
D The reaction produces a 100% yield of NH3.
Your answer [1]
© OCR 2025
, 3
2 The graph shows the volume of gas produced during a reaction.
A tangent has been drawn at 50 seconds. The gradient of the tangent gives the rate of reaction.
100
90
80
70
60
70
Volume of gas (cm3) 50
40
30
20
100
10
0
0 50 100 150 200
Time (s)
What is the rate of reaction, in cm3 / s, at 50 seconds?
A 0.56
B 0.70
C 1.1
D 1.4
Your answer [1]
© OCR 2025 Turn over
, 4
3 What are the optimum reaction conditions for the cracking of hydrocarbons?
Temperature (°C) Catalyst
A 25 not used
B 25 alumina
C 650 alumina
D 650 not used
Your answer [1]
4 Why do reactions happen faster at higher temperatures?
A The activation energy increases.
B The particles are closer together.
C The particles collide with more energy.
D The size of the particles increases.
Your answer [1]
© OCR 2025
Combined Question Paper & Final Marking Scheme
Oxford Cambridge and RSA
Friday 13 June 2025 – Morning
GCSE (9–1) Combined Science A
(Gateway Science)
J250/10 Chemistry (Higher Tier)
*1862816814*
Time allowed: 1 hour 10 minutes
You must have:
• a ruler (cm/mm)
• the Data Sheet for GCSE (9–1) Combined Science A
H
(Chemistry) (inside this document)
You can use:
• a scientific or graphical calculator
• an HB pencil
* J 2 5 0 1 0 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined pages at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 60.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 24 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/8687/2] OCR is an exempt Charity
DC (WW/CB) 351886/4 Turn over
, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 The equation shows a reaction that has reached dynamic equilibrium.
N2(g) + 3H2(g) 2NH3(g)
Which statement explains why this reaction is a dynamic equilibrium?
A N2 and H2 are gases.
B The rates of the forward and reverse reactions are equal.
C The reaction has stopped.
D The reaction produces a 100% yield of NH3.
Your answer [1]
© OCR 2025
, 3
2 The graph shows the volume of gas produced during a reaction.
A tangent has been drawn at 50 seconds. The gradient of the tangent gives the rate of reaction.
100
90
80
70
60
70
Volume of gas (cm3) 50
40
30
20
100
10
0
0 50 100 150 200
Time (s)
What is the rate of reaction, in cm3 / s, at 50 seconds?
A 0.56
B 0.70
C 1.1
D 1.4
Your answer [1]
© OCR 2025 Turn over
, 4
3 What are the optimum reaction conditions for the cracking of hydrocarbons?
Temperature (°C) Catalyst
A 25 not used
B 25 alumina
C 650 alumina
D 650 not used
Your answer [1]
4 Why do reactions happen faster at higher temperatures?
A The activation energy increases.
B The particles are closer together.
C The particles collide with more energy.
D The size of the particles increases.
Your answer [1]
© OCR 2025
