A technician is checking two proposed molecular formulae for hydrocarbons against the homologous series of alkenes. Sample P is known to be an alkene.
| Sample | Molecular formula |
|---|---|
| P | C3H6\text{C}_3\text{H}_6C3H6 |
| Q | CH2\text{CH}_2CH2 |
Give the name of sample P.
Explain why sample Q cannot be an alkene.