Chemistry — A-Level

Alkanes — Multiple-Choice Questions (Cambridge International A-Level Chemistry): Exam Questions

Exam code:9701

11 questions · 11 marks · ≈ 11 min

Guided practice

11 markeasy

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

Choose your answer

C₂H₅Cl + Cl• → C₂H₄Cl• + HCl

C₂H₅• + Cl• → C₂H₅Cl

C₂H₆ + Cl• → C₂H₅Cl + H•

C₂H₆ + H• → C₂H₅• + HCl

21 markeasy

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?

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C₈H₁₆ + 16NO → 8CO + 8N₂ + 8H₂O

C₈H₁₆ + 24NO → 8CO₂ + 12N₂ + 8H₂O

C₈H₁₈ + 17NO → 8CO + 8 $\frac{1}{2}$ N₂ + 9H₂O

C₈H₁₈ + 25NO → 8CO₂ + 12 $\frac{1}{2}$ N₂ + 9H₂O

31 markeasy

The hydrocarbon C₁₇H₃₆ can be cracked.

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

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C₃H₈

C₄H₈

C₈H₁₆

C₁₆H₃₄

41 markeasy

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?

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CH₃Cl

CH₃CH₂CH₂Cl

CH₃CH₂CH₂CH₃

CH₃CH₂CH₂CH₂CH₃

51 markmedium

The cracking of a single hydrocarbon molecule, C_nH_2n+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?

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61 markmedium

Which hydrocarbon would not be collected in the inverted tube by heating pentane, CH₃(CH₂)₃CH₃, in the apparatus shown?

Diagram of cracking apparatus: a horizontal tube containing pentane on mineral fibre and aluminium oxide heated strongly, connected by a delivery tube to an inverted test tube submerged in water for gas collection

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CH₄

CH₃CH₃

CH₃CH₂CH=CH₂

CH₃(CH₂)₈CH₃

71 markmedium

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?

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C₂H₄

C₂H₆

C₄H₄

C₄H₈

81 markmedium

Which statement about the free-radical substitution of ethane with chlorine is correct?

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Propagation steps involve the collision of two radicals to form a stable molecule

The final mixture will only contain chloroethane and hydrogen chloride

The initiation step involves heterolytic fission of a C–H bond

Ultraviolet light is required to provide the activation energy for the homolytic fission of Cl–Cl bonds

91 markhard

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?

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101 markhard

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?

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9.5

13.5

111 markhard

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?

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Butane, butene, hexene, octane

Butene, octane, pentene, propene

Ethane, hexene, heptene, pentene

Ethene, hexane, heptene, pentene