The reaction of $t-$butyl bromide with sodium methoxide mainly gives .............

Which of the following is most reactive towards $S_N2$ reaction?

Given below are two statements:
Statement $I$: $(Et)_2N-CH_2CH_2Cl$ will undergo alkaline hydrolysis at a faster rate than $(Et)_2CH-CH_2CH_2Cl$.
Statement $II$: Intramolecular substitution takes place first by involving the lone pair of electrons on nitrogen.
In the light of the above statements,choose the most appropriate answer from the options given below:

The major product of the following reaction is:

$A$ primary alkyl halide $(a)$ with molecular formula $C_{4}H_{9}Br$ reacts with alcoholic $KOH$ to give compound $(b)$. Compound $(b)$ reacts with $HBr$ to give compound $(c)$,which is an isomer of $(a)$. When $(a)$ reacts with sodium metal,it gives compound $(d)$ with molecular formula $C_{8}H_{18}$,which is different from the compound formed when $n$-butyl bromide reacts with sodium. Identify the structural formula of $(a)$ and write the equations for all the reactions.

Explain: Whether a haloalkane undergoes an elimination reaction or a substitution reaction.