Which process converts olefins into paraffins?

Ethylene possesses:

Predict the major product formed when $HCl$ is added to $2-$methylprop$-1-$ene $(isobutylene)$. Explain the mechanism involved.

Unbranched alkenes on ozonolysis give $:-$

Explain the reactivity of alkenes towards electrophilic reagents.

The product obtained by the reaction of propene with $HI$ in the presence of peroxide is.....