Pearson Edexcel IGCSE · Chemistry

Alkanes: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Alkanes.

10 questions29 marksFree, no account

Question 1

1 mark

An unbranched alkane molecule contains 12 carbon atoms. Using the general formula for alkanes, \(C_nH_{2n+2}\) , what is the total number of hydrogen atoms in this molecule?

Question 2

1 mark

In the substitution reaction between methane and chlorine in the presence of ultraviolet radiation, dichloromethane (\(CH_2Cl_2\)) can react further with chlorine. What is the name and formula of the organic product formed immediately following dichloromethane?

Question 3

1 mark

Alkanes are described as saturated hydrocarbons. What does the term saturated signify in this context?

Question 4

1 mark

Methane ( \(CH_4 \)) reacts with chlorine gas ( \(Cl_2 \)) in the presence of ultraviolet (UV) radiation via a substitution reaction. If the reaction is limited strictly to mono-substitution, what is the chemical formula of the organic product formed?

Question 5

1 mark

How is the chemical reactivity of an alkane, such as methane, typically described and classified, compared to an alkene, such as ethene?

Question 6

2 marks

State the general formula for alkanes and explain what is meant by the term saturated when describing these hydrocarbons.

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Question 7

3 marks

Explain why alkanes are classified as saturated hydrocarbons.

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Question 8

6 marks

An unknown unbranched alkane has a relative molecular mass (\(M_r\)) of 72. Calculate its molecular formula and state its name. (Relative atomic masses: \(C = 12, H = 1\))

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Question 9

5 marks

Alkanes are an important homologous series of hydrocarbons.
a) Define the term homologous series.
b) State the general formula for alkanes.
c) Butane ( \(C_4H_{10} \) ) is an alkane. Write a balanced chemical equation for the complete combustion of butane.
d) Explain why incomplete combustion of alkanes is harmful to humans and the environment.

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Question 10

8 marks

Alkanes react with halogens under specific conditions and can exist as different structural isomers.
a) Methane (\(CH_4\)) reacts with bromine (\(Br_2\)) to produce bromomethane and hydrogen bromide. Identify the type of reaction<\/b> occurring and state the essential condition<\/b> required for this reaction to proceed.
b) Write a balanced chemical equation for the reaction between methane and bromine described in part (a).
c) Pentane (\(C_5H_{12}\)) has three structural isomers. Define the term structural isomerism<\/b>.
d) Draw the displayed formulae<\/b> for the two branched-chain<\/i> isomers of pentane and provide the IUPAC name<\/b> for each isomer.<\/p>

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