Each sample contains a hydrocarbon that is either an alkane or an alkene.
| Sample | Molecular formula |
|---|---|
| P | C2H4\text{C}_2\text{H}_4C2H4 |
| Q | C2H6\text{C}_2\text{H}_6C2H6 |
| R | C4H8\text{C}_4\text{H}_8C4H8 |
| S | C4H10\text{C}_4\text{H}_{10}C4H10 |
Which pair of samples contains hydrocarbons from the alkene homologous series?
Samples P and R
Samples Q and S
Samples R and S
Samples P and Q