Each of these fuels burns completely in oxygen to form carbon dioxide and water.
Which fuel needs the greatest number of oxygen molecules, O2\mathrm{O_{2}}O2, to burn one molecule of the fuel?
Methane, CH4\mathrm{CH_{4}}CH4
Ethane, C2H6\mathrm{C_{2}H_{6}}C2H6
Ethene, C2H4\mathrm{C_{2}H_{4}}C2H4
Ethanol, C2H5OH\mathrm{C_{2}H_{5}OH}C2H5OH
63 exam-style questions on OCR GCSE Chemistry 6.2 Organic chemistry, covering 6.2.1 Crude oil and fractional distillation, 6.2.2 Cracking and dependence on hydrocarbons, 6.2.3 Functional groups and homologous series, 6.2.4 Reactions of alkanes, alkenes and alcohols, 6.2.5 Addition polymerisation and repeat units, 6.2.6 Naturally occurring polymers, 6.2.7 Chemical cells and fuel cells, and 6.2.8 Condensation polymerisation and how to make one. Each one has a worked solution and a mark scheme showing where the marks go.