Question

what type of alkyl group is an isobutyl group​

Answer 1

$\huge{\mathbb{\orange{ANSWER}}}$

Removing a hydrogen atom from a primary carbon atom of isobutane gives a primary alkyl group called the isobutyl group. Removing a hydrogen atom from the tertiary carbon atom of isobutane gives a tertiary alkyl group called the tert-butyl (t-butyl) group. Thus, there are four isomeric C4H9 alkyl groups.