1.1. Crude oil is extracted from underground rock formations and is used as a source of many useful chemicals.

Crude oil contains many different hydrocarbons.

What is meant by the term hydrocarbon?

1.2. Alkanes are the main type of hydrocarbon found in crude oil. Give the general formula for the alkanes.

1.3. Crude oil can be separated into useful fractions using fractional distillation.

Explain how crude oil is separated into fractions by fractional distillation.

1.4. Cracking is used to break down long-chain hydrocarbons into smaller, more useful molecules. Octane (C₈H₁₈) can be cracked to produce hexane (C₆H₁₄) and ethene (C₂H₄).

Balance the symbol equation for this reaction.

C₈H₁₈ → C_{_}H_{_} + C₆H₁₄

1.5. A student adds bromine water to one of the products of cracking.

Describe the result of this test if the product is an alkene and state what this shows.