• # question_answer Which of the following is the example of $S{{N}^{2}}$ reaction [CPMT 1999] A) $C{{H}_{3}}Br+O{{H}^{-}}-C{{H}_{3}}OH+B{{r}^{-}}$ B) $\underset{\underset{\,Br\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OH\,\,\,}{\mathop{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,}}\,}{\mathop{C{{H}_{3}}CHC{{H}_{3}}+O{{H}^{-}}\xrightarrow{{}}C{{H}_{3}}CHC{{H}_{3}}+B{{r}^{-}}}}\,$ C) $C{{H}_{3}}C{{H}_{2}}OH\xrightarrow{-{{H}_{2}}O}C{{H}_{2}}=C{{H}_{2}}$ D) $\underset{\underset{\,Br\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,H\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}{\mathop{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}}\,}{\mathop{\overset{\overset{C{{H}_{3}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{{H}_{3}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,}{\mathop{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}}\,}{\mathop{C{{H}_{3}}-C-C{{H}_{3}}+O{{H}^{-}}\to C{{H}_{3}}-C-O-C{{H}_{3}}+B{{r}^{-}}}}\,}}\,$

Only 1° alkyl halides, i.e. $C{{H}_{3}}Br$ undergoes ${{S}_{N}}2$ reaction.