Rate of $S_N2$ reactions depends on :

Ethyl bromide gives ethylene when reacted with

Tertiary alkyl halides are practically inert to $SN^2$ mechanism because of....

Dehydrohalogenation in monohaloalkanes produces

$A$ 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.

Which of the following chiral compounds undergoes nucleophilic substitution by $OH^-$ ions to form a racemic mixture?
$(a)$ $CH_3-CH(Br)-C_2H_5$
$(b)$ $CH_3-C(Br)(CH_3)-C_2H_5$
$(c)$ $CH_3-CH(C_2H_5)-CH_2Br$