Crude oil is a complex mixture of hydrocarbons that is separated into useful fractions using fractional distillation.
Which statement correctly describes the properties of these fractions or the separation process?
Fractions collected near the top of the column are highly volatile and have higher viscosities than fractions collected near the bottom.
Molecules in the fractions collected near the bottom of the column have larger surface areas, leading to stronger temporary dipole-induced dipole (London) forces between molecules.
Fractional distillation is a chemical process during which covalent bonds within the hydrocarbon chains are broken and reformed.
The refinery gas fraction obtained at the top of the column consists mainly of short-chain, unsaturated hydrocarbons such as ethene.
130 exam-style questions on Edexcel GCSE Chemistry 9.1 Fuels, covering 9.1.1 Hydrocarbons and crude oil, 9.1.2 Fractional distillation of crude oil and its fractions, 9.1.3 The alkanes as a homologous series, 9.1.4 Complete and incomplete combustion, 9.1.5 Pollutants from burning fuels, 9.1.6 Hydrogen as a fuel and non-renewable fossil fuels, and 9.1.7 Cracking of larger alkanes. Each one has a worked solution and a mark scheme showing where the marks go.