1 Choose from the following compounds to answer the questions. H H H3C H3C CH3 H H O C C H H H3C H C H H3C CH3 CH3 C H3C H O C C H O H O O C H C O H H H3C C CH2 C CH3 A B C D E CH CH3 H3C H O C C O H G F CH3 Each compound may be used once, more than once or not at all. (a) State which compound: (i) has a molecule with only 14 atoms … [1] (ii) can be oxidised to form propanoic acid … [1] (iii) is an isomer of butane … [1] (iv) reacts with steam to make an alcohol … [1] (v) can be polymerised to make a polyester. … [1] (b) State which two compounds in aqueous solution turn blue litmus red. … [1] [Total: 6]

1(a)(i) E 1 1(a)(ii) A 1 1(a)(iii) E 1 1(a)(iv) D 1 1(a)(v) F 1 1(b) C and F 1 To earn marks, you must correctly identify the specific compound (A, B, C, D, E, F, or G) that matches each chemical description or property.

1 Choose from the following compounds to answer the questions. C C H H3C H3C CH3 CH3 CH3 CH3 H2C H3C H3C H2C CH2 CH2 C O C H H H H H H A O C C H H O H F D C O C H O O CH3 C O C H H H C CH3 G O H2N C O C H CH3 H H H H H H C H3C C H E B Each compound may be used once, more than once or not at all. (a) State which compound: (i) has a molecule with only 11 atoms … [1] (ii) is oxidised to form ethanoic acid … [1] (iii) is an isomer of butene … [1] (iv) reacts with hydrogen in the presence of a catalyst to make an alkane … [1] (v) contains four different elements chemically combined. … [1] (b) Identify two compounds that have a pH of less than 7 in aqueous solution. … [1] [Total: 6]

1(a)(i) C 1 1(a)(ii) A 1 1(a)(iii) B 1 1(a)(iv) D 1 1(a)(v) H 1 1(b) C and F 1 To earn marks, you must correctly identify the specific compound (A, B, C, D, E, F, G, H) that matches each description, and for part (b), identify both compounds C and F.

2 This question is about pollutant gases. (a) Hydrocarbons such as octane are used as fuels for cars. The list shows the gases present in a car exhaust. carbon dioxide carbon monoxide nitrogen nitrogen dioxide octane water vapour State which two gases in the list show that incomplete combustion has taken place in this car engine. 1 … 2 … [2] (b) Describe a test for carbon dioxide. test … observation … [2] (c) Two natural sources of methane in the atmosphere are from leaks of natural gas and waste gases from animals. Give one other natural source of methane in the atmosphere. … [1] (d) Complete this sentence about the effect of an increase in the concentration of methane in the atmosphere. Methane is a … gas because it absorbs and then re-emits infrared radiation. This contributes to an increase in temperature of the atmosphere which is called … … . [2] (e) Cars are fitted with catalytic converters to reduce the amount of harmful pollutant gases from car exhausts. Describe how catalytic converters remove pollutant gases from car exhausts. … … … … … [3] [Total: 10]

2(a) carbon monoxide (1) octane (1) 2 2(b) limewater (1) turns milky / turns cloudy / white precipitate (1) 2 2(c) decomposition of vegetation / decomposition of plants 1 2(d) greenhouse (1) global warming (1) 2 2(e) mention of nitrogen oxides and carbon monoxide (as the pollutants / reactants) (1) nitrogen / N2 (in exhaust gases) (1) carbon dioxide / CO2 (in exhaust gases) (1) 3 (a) To earn these two marks, you must identify both carbon monoxide and octane as the gases indicating incomplete combustion. (b) To earn these two marks, you must state that limewater is used for the test and that the observation is it turning milky or cloudy. (c) To earn this mark, you must state 'decomposition of vegetation' or 'decomposition of plants' as a natural source of methane. (d) To earn these two marks, you must correctly identify methane as a 'greenhouse' gas and state that its increased concentration leads to 'global warming'. (e) To earn these three marks, you must mention nitrogen oxides and carbon monoxide as the pollutants/reactants, and then state that nitrogen and carbon dioxide are present in the exhaust gases.

3 Petroleum (crude oil) is a mixture of hydrocarbons. (a) Petroleum (crude oil) is separated into fractions such as liquefied petroleum gas, petrol (gasoline) and naphtha. (i) Name the process used to separate petroleum (crude oil) into fractions. … [1] (ii) Name one other fraction separated from petroleum (crude oil). Give a large-scale use for this fraction. fraction … use … [1] (iii) Petroleum (crude oil) does not contain enough of the fractions that contain smaller hydrocarbon molecules such as petrol (gasoline). Petroleum contains a high proportion of larger hydrocarbon molecules such as naphtha. Describe how the demand for smaller hydrocarbon molecules is satisfied. … … … … [2] (b) The structure of chloroethene is shown. C C H H H Cl Chloroethene is the monomer used to make poly(chloroethene). Poly(chloroethene) is non-biodegradable. (i) Explain the meaning of the term non-biodegradable. … … [1] (ii) Describe one environmental problem caused by the disposal of non-biodegradable plastics. … … [1] (iii) Draw the partial structure of poly(chloroethene). Show at least two repeat units. [2] (iv) A factory uses 100 tonnes of chloroethene to make poly(chloroethene). Deduce the mass of poly(chloroethene) made. Assume the percentage yield is 100%. Explain your answer. … … [1] (v) Chloroethene reacts with hydrogen in the presence of a catalyst. Suggest the structure of the product of this reaction. [1] [Total: 10]

3(a)(i) fractional distillation 1 3(a)(ii) Any one from: diesel – fuel for cars or lorries (1) paraffin / kerosene – heating / cooking / aviation fuel (1) bitumen – water proofing / roofing / road surfaces (1) heating oil – fuel for heating (1) lubricating or heavy oils – lubrication / fuels for ships (1) 1 3(a)(iii) cracking / heating strongly (in presence of a catalyst) (1) large hydrocarbons or naphtha fraction broken down / (1) 2 3(b)(i) cannot be decayed / cannot be decomposed (by natural or bacterial action) 1 3(b)(ii) incineration causes poisonous gases / litter / plastic waste in the sea / killing animals / takes up space in landfill sites 1 3(b)(iii) C C H H Cl H H C H H C Cl H H one repeat unit shown (1) at least two repeat units and extension bonds at both ends (1) 2 3(b)(iv) 100 tonnes because it is addition polymerisation / it is an addition reaction / no other product is produced 1 3(b)(v) CH3CH2Cl 1

Cambridge O Level Chemistry · 5070

O-Level Chemistry (5070) Organic chemistry past paper questions

Revise O-Level Chemistry (5070) — Organic chemistry with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

269 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Organic chemistry in O-Level Chemistry 5070 exams, 2020–2025

Across 2020–2025, Organic chemistry accounted for 244 questions worth 939 marks in Cambridge O Level Chemistry (5070) papers.

By year
Year	Questions	Marks
2020	52	187
2021	40	175
2022	37	128
2023	36	118
2024	36	148
2025	43	183

Most-tested subtopics

11.1 Formulae, functional groups and terminology410 marks
11.6 Alcohols355 marks
11.5 Alkenes321 marks

Appears in

Paper 1 · 159 qs
Paper 2 · 76 qs
Paper 3 · 2 qs
Paper 4 · 7 qs

All most-tested Chemistry topics

2021 May/Jun · Paper 2 · Q1 · 6 marks
Marking scheme
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2021 May/Jun · Paper 2 · Q1 · 6 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q2 · 10 marks
Marking scheme
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2021 May/Jun · Paper 2 · Q3 · 10 marks
$3 Petroleum (crude oil) is a mixture of hydrocarbons. (a) Petroleum (crude oil) is separated into fractions such as…$ $3 Petroleum (crude oil) is a mixture of hydrocarbons. (a) Petroleum (crude oil) is separated into fractions such as… (continued)$
Marking scheme
$Mark scheme: 3(a)(i) fractional distillation 1 3(a)(ii) Any one from: diesel – fuel for cars or lorries (1) paraffin / kerosene – heating…$ $Mark scheme: 3(a)(i) fractional distillation 1 3(a)(ii) Any one from: diesel – fuel for cars or lorries (1) paraffin / kerosene – heating… (continued)$ Get Steven’s plain-English explanation
2021 May/Jun · Paper 1 · Q16 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q16
Answer: C
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