Arrange in order of reactivity towards `S_(N)2` reactions:
(1) 2-bromo-2-methyibutane, 1 -bromopentane, 2-bromo pentane.

Explanation

The given bromoalkanes are isomeric compunds. `S_(N)2` reactivity of these alkyl bromides is determine by the hindrance at C-atom, undergoing nucleophilic attack, greater the steric hindrance, slower will be the reaction.

Thus, from the structures of the substrates we predict the following sequence of increasing reactivity: `A < C < B`.