Which of the following haloalkanes reacts with aqueous `KOH` most easily? Explain giving reason.

Explanation

2-bromo-2-methylpropane (ii), is a tertiary alkyl halide and it will forma stable carbocation on ionisation.
`underset("2-bromo-2-methylpropane")(H_(3)C-underset(CH_(3))underset(|)overset(Br)overset(|)C-CH_(3))underset(-Br^(-))overset("Ionisation")tounderset(3^(@) "carbocation" ("stable"))(H_(3)C-underset(CH_(3))underset(|)overset(+)C-CH_(3))overset(OH^(-))tounderset("2-methyl-2-propanal")(CH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)C-CH_(3))`
1-bromobutane is primary alkyl halide whereas 2-bromobutane and 2-chlorobutane is secondary alkyl halide.