Chemistry

Alkanes — Multiple-Choice Questions (Edexcel IAL Chemistry): Exam Questions

Exam code:YCH11

9 questions · 14 marks · ≈ 14 min

Guided practice

11 markeasy

All alkanes have the same

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empirical formula

general formula

molecular formula

structural formula

21 markeasy

A single molecule of decane, C₁₀H₂₂ , is cracked.

Which of these mixtures could not be formed?

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pentene and pentane

ethene, butene and butane

propene, propane and butene

hexene and propane

31 markeasy

Which pollutant cannot form when alkane fuels are burned in car engines?

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hydrogen chloride

sulfur dioxide

carbon particulates

carbon monoxide

42 marksmedium

(a)

Ethane reacts with bromine in the presence of ultraviolet radiation.

What is the equation for the reaction?

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C₂H₆ + Br₂ → C₂H₄Br₂ + H₂

C₂H₆ + Br₂ → C₂H₅Br + HBr

C₂H₆ + Br₂ → 2CH₃Br

C₂H₆ + Br₂ → CH₄ + CH₂Br₂

(b)

The ultraviolet radiation is needed for

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homolytic breaking of a Br–Br bond

heterolytic breaking of a Br–Br bond

homolytic breaking of a C–H bond

heterolytic breaking of a C–H bond

52 marksmedium

(a)

Methane reacts with excess chlorine in UV light.

Which process occurs in the initiation step?

q10a-paper-1-oct-2021-edexcel-ial-chemistry

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(b)

Which of these molecules could not be formed in a termination step?

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C₂H₆

CH₃Cl

CH₂Cl₂

HCl

61 markmedium

When C₂₀H₄₂ is cracked, each molecule produces one molecule of ethene, one molecule of butane and two molecules of hydrocarbon E.

What is the molecular formula of E?

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C₇H₁₃

C₇H₁₄

C₁₄H₂₆

C₁₄H₂₈

71 markmedium

Petrol, bioethanol and hydrogen are fuels.

All three of these fuels

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burn to produce greenhouse gases

are overall carbon neutral

are overall sustainable

biodegrade rapidly

84 marksmedium

(a)

Cyclopentane undergoes free radical substitution with bromine.

Which of these is an overall equation for this reaction?

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C₅H₈ + Br₂ → C₅H₈Br₂

C₅H₁₀ + Br₂ → C₅H₁₀Br₂

C₅H₁₀ + Br₂ → C₅H₈Br₂ + H₂

C₅H₁₀ + Br₂ → C₅H₉Br + HBr

(b)

Which statement is not correct about this reaction system?

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only the initiation step involves homolytic bond fission

only some bromine is converted to free radicals in the initiation step

propagation forms more product than termination

further substitution reactions are likely to occur

(c)

Which free radical is least likely to form in a propagation step in this reaction system?

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^C^₅ $H_{9}^{\bullet}$

B $r^{\bullet}$

C₅H₈B $r^{\bullet}$

$H^{\bullet}$

(d)

Which alkane could be formed in a termination step in this reaction system?

q16d-paper-1-jan-2021-edexcel-ial-chemistry

Choose your answer

91 markmedium

Which of these is a correct propagation step in the free radical substitution of methane by chlorine?

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Cl₂ → 2Cl•

CH₃• + Cl₂ → CH₃Cl + Cl•

CH₄ + Cl₂ → CH₃Cl + HCl

2Cl• → Cl₂

84 marksmedium

(a)

Cyclopentane undergoes free radical substitution with bromine.

Which of these is an overall equation for this reaction?

Choose your answer

C₅H₈ + Br₂ → C₅H₈Br₂

C₅H₁₀ + Br₂ → C₅H₁₀Br₂

C₅H₁₀ + Br₂ → C₅H₈Br₂ + H₂

C₅H₁₀ + Br₂ → C₅H₉Br + HBr

(b)

Which statement is not correct about this reaction system?

Choose your answer

only the initiation step involves homolytic bond fission

only some bromine is converted to free radicals in the initiation step

propagation forms more product than termination

further substitution reactions are likely to occur

(c)

Which free radical is least likely to form in a propagation step in this reaction system?

Choose your answer

^C^₅ $H_{9}^{\bullet}$

B $r^{\bullet}$

C₅H₈B $r^{\bullet}$

$H^{\bullet}$

(d)

Which alkane could be formed in a termination step in this reaction system?

q16d-paper-1-jan-2021-edexcel-ial-chemistry

Choose your answer