Question

Alkanes undergo only substitution reactions but alkenes and alkynes undergo both substitution and addition reactions. Why?

Answer 1

Auditor reaction involves addition of move atones to the

molecule or compound so usually $\pi$-bonds are takes away

and used as $\sigma$-bonds with the new atoms, ether than already

present $\sigma -$ bonds being recreated

As it is easier to break $\pi$ than $\sigma$

Alkanes do not undergo addition reaction because they already

only have single $\sigma -$ bounds, which cannot be more started

future and thus can only be swapped ( that give lies to

substitution reactions)