Classify the following reactions in one of the reaction type studied in this unit.
(a) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{HS}^{-} \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{SH}+\mathrm{Br}^{-}$
(b) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{HCl} \rightarrow\left(\mathrm{CH}_{3}\right)_{2} \mathrm{ClC}-\mathrm{CH}_{3}$
(c) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br}+\mathrm{HO}^{-} \rightarrow \mathrm{CH}_{2}=\mathrm{CH}_{2}+\mathrm{H}_{2} \mathrm{O}+\mathrm{Br}^{-}$
(d) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{CH}_{2} \mathrm{OH}+\mathrm{HBr} \rightarrow\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CBrCH}_{2} \mathrm{CH}_{3}+\mathrm{H}_{2} \mathrm{O}$
(a) It is an example of substitution reaction as in this reaction the bromine group in bromoethane is substituted by the –SH group.
(b) It is an example of addition reaction as in this reaction two reactant molecules combine to form a single product.
(c) It is an example of elimination reaction as in this reaction hydrogen and bromine are removed from bromoethane to give ethene.
(d) In this reaction, substitution takes place, followed by a rearrangement of atoms and groups of atoms.