Write the equation for the preparation of $1$-iodobutane from but-$1$-ene.

Which compound in each of the following pair will react faster in ${\mathrm{S}}_{\mathrm{N}}2$ reaction with ${\mathrm{OH}}^{-}$?

$({\mathrm{CH}}_3{)}_3\mathrm{CCl} \mathrm{or} {\mathrm{CH}}_3\mathrm{Cl}$

How will you bring about the following conversion?

Ethane to bromoethene