There are four isomers of the compound having the formula C4H9Br. These isomers are
given below.

$\stackrel{4}{C}{H}_3—\stackrel{3}{C}{H}_2—\stackrel{2}{C}{H}_2 —\stackrel{1}{C}{H}_2— Br$

1−Bromobutane

(b) $$
$Br$
$\stackrel{4}{C}{H}_3—\stackrel{3}{C}{H}_3 \stackrel{2|}{C}H \stackrel{1}{C}{H}_3$

2−Bromobutane

(c) $C{H}_3$
$|$
$\stackrel{3}{C}{H}_3— \stackrel{2}{C}H— \stackrel{1}{C}{H}_2 \mathbf{—}Br$

1−Bromo−2−methylpropane

(d) $Br$
$|$
$\stackrel{3}{C}{H}_3—\stackrel{2}{C}— \stackrel{1}{C}{H}_3$
$|$
$C{H}_3$

2−Bromo−2−methylpropane