Free Alkanes & alkenes questions for IGCSE Chemistry (0620), part of Organic chemistry. Each question has the answer and the marking points an examiner would look for.
Generate a full Alkanes & Alkenes worksheet →All Organic chemistry questionsEthene reacts separately with bromine, with steam and with hydrogen.
Which row shows the products?
| with bromine | with steam | with hydrogen | |
|---|---|---|---|
| A | CH2BrCH2Br | CH3COOH | CH3CH3 |
| B | CH3CH2Br | CH3CH2OH | CH3CH3 |
| C | CH2BrCH2Br | CH3CH2OH | CH3CH3 |
| D | CH2BrCH2Br | CH3CH2OH | CH2CH2 |
Answer: C
Ethanoic acid reacts with propan-1-ol to form an ester.
What are the name and the structural formula of the ester?
| name | structural formula | |
|---|---|---|
| A | propyl ethanoate | CH3COOCH2CH2CH3 |
| B | ethyl propanoate | CH3CH2COOCH2CH3 |
| C | ethyl propanoate | CH3COOCH2CH2CH3 |
| D | propyl ethanoate | CH3CH2COOCH2CH3 |
Answer: A
Fig. 3.1 shows the displayed formula of compound Q.
Name compound Q.
State the homologous series to which Q belongs.
Write the molecular formula of Q.
Describe a test to distinguish an alkane from an alkene. Give the result for each.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | propene propene B1 | 1 |
| (b) | alkenes alkenes B1 | 1 |
| (c) | C3H6 C3H6 B1 | 1 |
| (d) | Bromine water: alkene decolourises it (orange to colourless); alkane: stays orange aqueous bromine / bromine water B1 alkene: orange → colourless B1 alkane: remains orange B1 | 3 |
Ethene can be made by cracking long-chain alkanes.
Describe the conditions used for cracking.
Explain why cracking is important to the petrochemical industry.
Describe a test to distinguish ethene from ethane.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | high temperature; catalyst high temperature B1 catalyst (e.g. silica/alumina) or steam B1 | 2 |
| (b) | supply of short-chain fuels and alkenes there is more demand for short-chain alkanes (petrol) than supply B1 it also produces alkenes for making polymers B1 | 2 |
| (c) | bromine water decolourises with ethene add bromine water B1 ethene decolourises it (orange to colourless), ethane does not B1 | 2 |
Alkanes are used as fuels.
Write a balanced equation for the complete combustion of propane, C₃H₈.
State what is meant by a saturated hydrocarbon.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | C₃H₈ + 5O₂ → 3CO₂ + 4H₂O correct formulae B1 balanced B1 | 2 |
| (b) | only single C–C bonds contains only single carbon–carbon bonds B1 | 1 |
Large alkane molecules such as C10H22 are cracked to make smaller, more useful molecules.
State the conditions used for catalytic cracking.
One molecule of C10H22 is cracked into one molecule of octane, C8H18, and ethene only. Write the equation.
Describe a test that shows that ethene is unsaturated. Give the result.
Ethene reacts with steam to make ethanol. State the conditions and the type of reaction.
Ethanol is oxidised to ethanoic acid, which then reacts with ethanol. Name the product and draw its displayed formula.
Draw one repeat unit of the addition polymer made from propene, CH3CH=CH2.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | high temperature and a catalyst (e.g. 600–700 °C, alumina/silica/zeolite) high temperature B1 catalyst B1 | 2 |
| (b) | C10H22 → C8H18 + 1C2H4 correct formulae B1 balanced with 1C2H4 B1 | 2 |
| (c) | Add bromine water: orange to colourless bromine (water) B1 orange → colourless (decolourised) B1 | 2 |
| (d) | 300 °C, 60 atm, phosphoric acid catalyst; addition (hydration) temperature ~300 °C and pressure ~60 atm B1 (phosphoric) acid catalyst B1 addition B1 | 3 |
| (e) | ethyl ethanoate, CH3COOCH2CH3 ethyl ethanoate B1 ester linkage –COO– shown B1 all atoms and bonds correct B1 | 3 |
| (f) | –[CH2–CH(CH3)]– with continuation bonds two carbons in chain with CH3 side group B1 continuation bonds at both ends B1 | 2 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in