Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Cracking — exam questions
12 original Incandio exam-style questions on cracking, 26 marks, about 26 minutes of writing. Each one carries the command word, the tariff and the specification statement it assesses, exactly as a paper presents them. This is an original Incandio practice question, written to reflect the structure and demands of the qualification. It is not an official Pearson Edexcel past-paper question.
This is the practice set for Cracking — the lesson that teaches it. Read the lesson first if the idea is new; come here when you want to find out whether you can turn it into marks. Completely free, no account needed to read.
What these questions ask of you
9 command words run through this set, and on Pearson Edexcel International GCSE Chemistry each one means something precise. Answering the wrong command is the commonest way a candidate who understands the lesson still loses the mark.
- Which (1 mark)
- one option chosen from the set given
- Name (1 mark)
- the correct chemical name
- Give (1–2 marks)
- a short factual answer — the most common chemistry command
- Describe (2–5 marks)
- developed, linked statements of what happens or what is observed Misread as: giving one bare observation where the tariff asked for a developed account
- Write (1–3 marks)
- the equation, formula or ionic equation, balanced, with state symbols where asked
- Explain (2–4 marks)
- the reason, in terms of particles, bonding, energy or equilibrium Misread as: describing the observation without giving the chemistry that causes it
- Suggest (1–3 marks)
- a plausible answer applying taught chemistry to an unfamiliar substance
- Identify (1–2 marks)
- the correct substance or feature selected from what is given
- Calculate (1–4 marks)
- a numerical answer with working, to the stated precision
Assessed on Paper 1 (4CH1/1C) and Paper 2 (4CH1/2C), against AO1, AO2, AO3.
Where these sit in the specification
Pearson Edexcel International GCSE Chemistry (4CH1) — statements 4.17 · 4.18. Incandio is aligned to this specification; it is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording.
The 12 questions
Answer them on paper, then open the lesson's exam practice to have them marked. The mark scheme, the accepted and rejected answers and the annotated model answer are in Incandio and are not printed here — an answer beside its question is not practice.
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Table 1 — a typical barrel of crude oil compared with demand Fraction Percentage in crude oil Percentage of demand refinery gases 2 4 petrol 16 27 kerosene 13 8 diesel oil 19 23 fuel oil and bitumen 50 38 (a)
(1)Identify
Identify the fraction in Table 1 with the largest shortfall between supply and demand.
Table 1 — a typical barrel of crude oil compared with demand Fraction Percentage in crude oil Percentage of demand refinery gases 2 4 petrol 16 27 kerosene 13 8 diesel oil 19 23 fuel oil and bitumen 50 38 (b)
(2)Calculate
Calculate the surplus of fuel oil and bitumen, as a percentage of the barrel, using Table 1.
Table 1 — a typical barrel of crude oil compared with demand Fraction Percentage in crude oil Percentage of demand refinery gases 2 4 petrol 16 27 kerosene 13 8 diesel oil 19 23 fuel oil and bitumen 50 38 ............................ %
(c)
(3)Explain
Explain how cracking helps a refinery deal with the figures in Table 1.
Table 1 — a typical barrel of crude oil compared with demand Fraction Percentage in crude oil Percentage of demand refinery gases 2 4 petrol 16 27 kerosene 13 8 diesel oil 19 23 fuel oil and bitumen 50 38 (d)
(3)Suggest
Table 1 shows kerosene in surplus as well. Suggest why a refinery would be far more reluctant to crack kerosene than fuel oil.
Table 1 — a typical barrel of crude oil compared with demand Fraction Percentage in crude oil Percentage of demand refinery gases 2 4 petrol 16 27 kerosene 13 8 diesel oil 19 23 fuel oil and bitumen 50 38 (Total for Question 1 = 9 marks)
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(1)Which
Which is always produced when a long-chain alkane is cracked?
Product A carbon dioxide B an alkene C an alcohol D hydrogen only (Total for Question 2 = 1 mark)
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(1)Name
Name a catalyst used in catalytic cracking.
(Total for Question 3 = 1 mark)
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(1)Give
Give the approximate temperature used for catalytic cracking.
(Total for Question 4 = 1 mark)
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(2)Describe
Describe what happens to a long-chain alkane molecule during cracking.
(Total for Question 5 = 2 marks)
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(2)Write
Write a balanced equation for the cracking of decane, C₁₀H₂₂, into octane and one other product.
(Total for Question 6 = 2 marks)
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(3)Explain
Explain why cracking is carried out in oil refineries.
(Total for Question 7 = 3 marks)
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(3)Suggest
Suggest why the catalyst allows cracking to be carried out at a much lower temperature than would otherwise be needed, and why that matters to a refinery.
(Total for Question 8 = 3 marks)
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(4)Explain
A sample of dodecane is cracked and the products are shaken with bromine water. Explain why the bromine water is decolourised even though dodecane itself would not decolourise it.
(Total for Question 9 = 4 marks)
Have them marked, then defend the answer
Practice tells you the mark; teaching it back tells you whether you understand it. On Incandio a topic counts as mastered only once you have taught it and defended it.
- Mark these questions — 12 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain cracking to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Vladimir Shukhov over three rounds, marked against descriptors you can read first.
Completely free. No subscriptions, no paywalls, no account needed to start.
Back to the lesson
- Cracking — Breaking long molecules nobody wants into short ones everybody does — and the reason a refinery has to.
- All of Incandio Chemistry · Incandio Exam Practice