GCSE Chemistry B OCR J258/03 Breadth in Chemistry chemistry exam paper Twenty First Century Science atomic structure bonding rates of reaction energy changes periodic trends environmental chemistry exam paper with mark scheme science assessmen

20251202204444_692f4fbcc7ae1_ngcr__92_.docx
20251202204444_692f4fbcc7ae1_ngcr__92_.docx
20251202204444_692f4fbcc7ae1_ngcr__92_.docx




2025 OCR GCSE Chemistry B (Twenty First Century Science)
J258/03 Breadth in Chemistry (Higher Tier)
Complete Question paper with Marking Scheme Combined




Monday 19 May 2025 – Morning
GCSE (9−1) Chemistry B (Twenty First Century Science)
J258/03 Breadth in Chemistry (Higher Tier)
Time allowed: 1 hour 45 minutes

You must have:
• a ruler (cm/mm)
• the Data Sheet for GCSE (9–1) Chemistry B
(inside this document)
You can use:
• a scientific or graphical calculator
• an HB pencil


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 90.
• The marks for each question are shown in brackets [ ].
• This document has 28 pages.

ADVICE
• Read each question carefully before you start your answer.




© OCR 2025 [601/8605/7] OCR is an exempt Charity
DC (IP/FC) 362110/8 Turn over


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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]




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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]




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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]




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