Hydrocarbon P undergoes cracking to produce compound Q and hydrogen. Compound R is then made by addition polymerisation of compound Q. To which homologous series do P, Q and R belong?
- Aalkene: P only; alkane: Q and R
- Balkene: Q only; alkane: P and R
- Calkene: P and Q; alkane: R only
- Dalkene: P and R; alkane: Q only