A LevelChemistryCIETopic Questions14. Hydrocarbons14.1 Alkanes

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First teaching 2023

First exams 2025

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Alkanes (CIE A Level Chemistry)

Topic Questions

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11 mark

Which equation represents a valid propagation step in the free radical reaction between ethane and chlorine?

  • C2H6 + Cl• rightwards arrow C2H5Cl + H•

  • C2H5Cl + Cl• rightwards arrow C2H4Cl• + HCl

  • C2H6 + H• rightwards arrow C2H5• + HCl

  • C2H5• + Cl• rightwards arrow C2H5Cl

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21 mark

One of the reactions taking place in a catalytic converter in a car exhaust system is between nitrogen oxide and octane (unburned petrol). The products of this reaction are non-toxic.

Which is the correct equation for the reaction?

  • C8H16 + 16NO rightwards arrow 8CO + 8N2 + 8H2O

  • C8H16 + 24NO rightwards arrow 8CO2 + 12N2 + 8H2O

  • C8H18 + 17NO rightwards arrow 8CO + 8 begin mathsize 16px style 1 half end style N2 + 9H2O

  • C8H18 + 25NO rightwards arrow 8CO2 + 12 begin mathsize 16px style 1 half end style N2 + 9H2O

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31 mark

The hydrocarbon C17H36 can be cracked.

Which compound is the least likely to be produced in this reaction?

  • C3H8

  • C4H8

  • C8H16

  • C16H34

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41 mark

In the presence of ultraviolet light, ethane and chlorine react to give a mixture of products.

Which compound could be present in the mixture of products?

  • CH3Cl

  • CH3CH2CH2Cl

  • CH3CH2CH2CH3

  • CH3CH2CH2CH2CH3

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11 mark

Samples of 10 cm3 of each of the first four members of the alkane series are separately mixed with 70 cm3 of oxygen. Each is then burned and the total volume, V, of residual gas measured again at room temperature and pressure.

Which graph represents the results that would be obtained?

  • 3-2-h-4a

  • 3-2-h-4b

  • 3-2-h-4c

  • 3-2-h-4d

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21 mark

The petrol additive tetraethyl-lead (IV), Pb(C2H5)4, is now banned in many countries. When it is completely burned in air, lead (II) oxide, CO2 and H2O are formed.

How many moles of oxygen are required to burn one mole of Pb(C2H5)4?

  • 9.5

  • 11

  • 13.5

  • 27

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31 mark

The cracking of eicosane, C20H42, produces a hydrocarbon that is in very high demand for transportation and also three consecutive members of the same homologous series of hydrocarbons.

What are the correct products of cracking for the given reaction?

  • Butene, octane, pentene, propene

  • Butane, butene, hexene, octane

  • Ethane, hexene, heptene, pentene

  • Ethene, hexane, heptene, pentene

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11 mark

The cracking of a single hydrocarbon molecule, CnH2n+2, produces two hydrocarbon molecules only. Each hydrocarbon product contains the same number of carbon atoms in one molecule.  Each hydrocarbon product has non-cyclic structural isomers. 

What is the value of n?

  • 9

  • 8

  • 6

  • 4

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21 mark

Which hydrocarbon would not be collected in the inverted tube by heating pentane,

CH3(CH2)3CH3, in the apparatus shown?

3-2-cie-ial-chemistry-diagram-q4medium

  • CH4

  • CH3CH3

  • CH3CH2CH=CH2

  • CH3(CH2)8CH3

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31 mark

0.200 mol of a hydrocarbon undergoes complete combustion to give 35.2 g of carbon dioxide and 14.4 g of water as the only products.

What is the molecular formula of the hydrocarbon?

  • C2H4

  • C2H6

  • C4H4

  • C4H8

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