Which compound in each of the following pairs will react faster in `S_(N)2` reaction with `""^(–)OH` ?
(i) `CH_(3)Br or CH_(3)I , (ii) (CH_(3))_(3)C Cl or CH_(3)Cl`

Explanation

(i) Since `I^(-)` ion is a better leaving group than `Br^(-)` ion, therefore, `CH_(3)I` reacts faster `CH_(3)Br` in `S_(N)2` reaction with `OH^(-)` ion.
(ii) On steric grouns, `1^(@)` alkyl halides are more reactive than tert-alkyl halides in `S_(N)2` reaction. therefore, `CH_(3)Cl` will react at a faster rate than `(CH_(3))_(3)C Cl` in a `S_(N)2` reaction with `OH^(-)` ion.