In \(\text{S}_\text{N}1\) reaction, the alkyl halide that on hydrolysis produces racemic mixture is

In an \(\text{S}_\text{N}1\) reaction, the formation of a racemic mixture occurs only if the product formed has a chiral center.

Tertiary butyl bromide on hydrolysis gives tertiary butyl alcohol, which is achiral.

2-bromobutane on hydrolysis forms a planar secondary carbocation intermediate. The nucleophile (water) can attack from either face of the planar carbocation with equal probability, leading to the formation of \(d\) and \(l\) enantiomers of 2-butanol. Since 2-butanol has a chiral carbon, a racemic mixture is produced.

Isopropyl bromide gives isopropyl alcohol, which is achiral.

Methyl bromide gives methyl alcohol, which is achiral.

Therefore, 2-bromobutane produces a racemic mixture.

Answer: 2-bromobutane