Alkenes are unsaturated aliphatic hydrocarbons containing at least one double bond between carbon atoms.

The simplest alkene is ethene ($C_2 H_4$), also known as ethylene.

Alkenes exhibit both chain isomerism and position isomerism starting from $n = 4$.

They undergo characteristic addition reactions due to the presence of the weaker $\pi$ ($\pi$) bond.

Used as important raw materials for manufacturing plastics like polyethylene.

Crucial starting materials for industrial synthesis of alcohols, epoxides, and synthetic rubber.

Lower alkenes are highly flammable and can form explosive mixtures with air.

Ripening of fruits using ethylene ($C_2 H_4$) gas.

Production of polymers such as PVC, polyethylene, and polystyrene.

Option A ($C_n H_{2n+1}$) represents alkyl groups (e.g., methyl, ethyl).

Option B ($C_{2n} H_{2n}$) is an incorrect rearrangement.

Option C ($C_n H_n$) represents aromatic compounds like benzene ($C_6 H_6$) or acetylene derivatives under specific conditions, not alkenes.