The reduction of chloroform with $Zn$ and $HCl$ (alc.) gives ..........

$Methyl$ chloride reacts with silver acetate to yield:

Explain the mechanism of a unimolecular nucleophilic substitution $(S_N1)$ reaction with a suitable example.

$A$ 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.

The reaction:
$CH_3CH_2I + KOH_{(aq)} \to CH_3CH_2OH + KI$
is classified as :

What are nucleophiles and nucleophilic substitution reactions? Provide a basic overview of the nucleophilic substitution reaction of haloalkanes.