When an alkane is cracked, at least one of the products is always an alkene.
Which statement explains why?
Alkanes are unstable at high temperatures, so all of the products contain double bonds.
The catalyst adds a double bond to every molecule that it breaks.
There are not enough hydrogen atoms in the alkane for all of the products to be alkanes.
Alkenes have higher boiling points than alkanes, so they are the only products that can be collected.
63 exam-style questions on OCR GCSE Chemistry 6.2 Organic chemistry, covering 6.2.1 Crude oil and fractional distillation, 6.2.2 Cracking and dependence on hydrocarbons, 6.2.3 Functional groups and homologous series, 6.2.4 Reactions of alkanes, alkenes and alcohols, 6.2.5 Addition polymerisation and repeat units, 6.2.6 Naturally occurring polymers, 6.2.7 Chemical cells and fuel cells, and 6.2.8 Condensation polymerisation and how to make one. Each one has a worked solution and a mark scheme showing where the marks go.