Chemistry - Hydrocarbon Question with Solution | TestHub

Chlorination of isobutane is poorly selective: reactivity 3°:1° ≈ 5:1 but there are 9 primary H vs 1 tertiary H, so 1-chloro-2-methylpropane is the major product X.
Bromination is highly selective for the tertiary C–H, giving tert-butyl bromide as Y.
Hence option (C).