GCSE CHEMISTRY B (TWENTY FIRST CENTURY SCIENCE) — Actual May 2025 PAST
PAPER: Breadth in Chemistry (Higher Tier). All Assessment Questions & Mark Scheme [OCR
J258/03]
Exam Resource Summary
The GCSE (9–1) Chemistry B (Twenty First Century Science) May 2025 Higher Tier Paper (OCR
J258/03) merges the full official examination paper with its detailed mark scheme to create a
comprehensive revision and practice resource. This paper assesses students’ understanding of a wide
range of chemical concepts, including atomic structure, bonding, chemical reactions, energetics, rates of
reaction, the periodic table, organic chemistry, and practical investigation skills. Candidates are expected
to apply knowledge to unfamiliar scenarios, analyse data, evaluate scientific information, and construct
coherent, evidence-based explanations. By presenting each question alongside its marking criteria, this
merged resource clarifies examiner expectations, highlights the analytical and evaluative skills required
for high-band marks, and guides learners in producing structured, accurate, and well-reasoned responses.
This integrated format supports targeted revision, strengthens exam technique, and prepares students
thoroughly for the 2026 OCR GCSE Chemistry B (Twenty First Century Science) Higher Tier Breadth in
Chemistry examination.
OCR is an exempt Charity
Turn over
, 2
1 A student investigates rate of reaction.
(a) The student does three experiments adding limestone to dilute hydrochloric acid.
In all three experiments, the student keeps these the same:
• the mass of limestone
• the volume of acid
• the concentration of acid.
In experiment 1 the student adds one large piece of limestone to the acid at 20 °C.
The student measures the volume of gas produced every 30 seconds.
Fig. 1.1 shows the results of experiment 1.
Fig. 1.1
50
40
30
Volume of gas
produced (cm3)
20
10
0
0 60 120 180 240 300 360 420 480 540 600
Time (s)
Calculate the rate of reaction during the first 120 seconds.
Use Fig. 1.1.
Give your answer to 2 decimal places.
Rate of reaction =................................................ cm3 / s [3]
© OCR 2025
, 3
(b) Table 1.1 shows the conditions used for all three experiments.
Table 1.1
Type of limestone Temperature (°C)
Experiment 1 Large piece 20
Experiment 2 Large piece 40
Experiment 3 Powder 40
(i) Draw a line on Fig. 1.1 to show the expected results for experiment 2.
Use the information in Table 1.1 to help you. [2]
(ii) Experiment 3 is the fastest.
Explain why.
Use the information in Table 1.1.
Include ideas about collisions in your answer.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [2]
© OCR 2025 Turn over
, 4
(c) A scientist investigates the effect of four metals, A, B, C and D, on the rate of reaction to make
ethane.
The scientist uses 5.0 g of each metal.
Table 1.2 shows their results.
Table 1.2
Mass of metal at end Time taken to make
Metal
of reaction (g) 10 g of ethane (s)
A 2.5 25
B 0.0 30
C 5.0 40
D 5.0 25
(i) Which metal A, B, C or D is the best metal to use as a catalyst in this reaction?
Explain your reasoning.
Use the information in Table 1.2.
Metal .....................................
Explanation ......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[2]
(ii) Which statements about catalysts are true and which are false?
Tick (✓) one box in each row.
True False
A catalyst changes the overall energy change for a reaction.
A catalyst lowers the activation energy of a reaction.
A catalyst provides an alternative route for a reaction.
[2]
© OCR 2025
PAPER: Breadth in Chemistry (Higher Tier). All Assessment Questions & Mark Scheme [OCR
J258/03]
Exam Resource Summary
The GCSE (9–1) Chemistry B (Twenty First Century Science) May 2025 Higher Tier Paper (OCR
J258/03) merges the full official examination paper with its detailed mark scheme to create a
comprehensive revision and practice resource. This paper assesses students’ understanding of a wide
range of chemical concepts, including atomic structure, bonding, chemical reactions, energetics, rates of
reaction, the periodic table, organic chemistry, and practical investigation skills. Candidates are expected
to apply knowledge to unfamiliar scenarios, analyse data, evaluate scientific information, and construct
coherent, evidence-based explanations. By presenting each question alongside its marking criteria, this
merged resource clarifies examiner expectations, highlights the analytical and evaluative skills required
for high-band marks, and guides learners in producing structured, accurate, and well-reasoned responses.
This integrated format supports targeted revision, strengthens exam technique, and prepares students
thoroughly for the 2026 OCR GCSE Chemistry B (Twenty First Century Science) Higher Tier Breadth in
Chemistry examination.
OCR is an exempt Charity
Turn over
, 2
1 A student investigates rate of reaction.
(a) The student does three experiments adding limestone to dilute hydrochloric acid.
In all three experiments, the student keeps these the same:
• the mass of limestone
• the volume of acid
• the concentration of acid.
In experiment 1 the student adds one large piece of limestone to the acid at 20 °C.
The student measures the volume of gas produced every 30 seconds.
Fig. 1.1 shows the results of experiment 1.
Fig. 1.1
50
40
30
Volume of gas
produced (cm3)
20
10
0
0 60 120 180 240 300 360 420 480 540 600
Time (s)
Calculate the rate of reaction during the first 120 seconds.
Use Fig. 1.1.
Give your answer to 2 decimal places.
Rate of reaction =................................................ cm3 / s [3]
© OCR 2025
, 3
(b) Table 1.1 shows the conditions used for all three experiments.
Table 1.1
Type of limestone Temperature (°C)
Experiment 1 Large piece 20
Experiment 2 Large piece 40
Experiment 3 Powder 40
(i) Draw a line on Fig. 1.1 to show the expected results for experiment 2.
Use the information in Table 1.1 to help you. [2]
(ii) Experiment 3 is the fastest.
Explain why.
Use the information in Table 1.1.
Include ideas about collisions in your answer.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
. ................................................................................................................................................. [2]
© OCR 2025 Turn over
, 4
(c) A scientist investigates the effect of four metals, A, B, C and D, on the rate of reaction to make
ethane.
The scientist uses 5.0 g of each metal.
Table 1.2 shows their results.
Table 1.2
Mass of metal at end Time taken to make
Metal
of reaction (g) 10 g of ethane (s)
A 2.5 25
B 0.0 30
C 5.0 40
D 5.0 25
(i) Which metal A, B, C or D is the best metal to use as a catalyst in this reaction?
Explain your reasoning.
Use the information in Table 1.2.
Metal .....................................
Explanation ......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[2]
(ii) Which statements about catalysts are true and which are false?
Tick (✓) one box in each row.
True False
A catalyst changes the overall energy change for a reaction.
A catalyst lowers the activation energy of a reaction.
A catalyst provides an alternative route for a reaction.
[2]
© OCR 2025
