The compound shown is 2-chloropentane (no configuration specified). The total number of isomers of molecular formula $\mathrm{C}{}_5\mathrm{H}{}_{11}\mathrm{Cl}$, counting constitutional isomers and enantiomers separately, is

Pentane skeleton: 1-, 2- and 3-chloropentane (3). 2-Methylbutane skeleton: 1-chloro-2-methylbutane, 2-chloro-2-methylbutane, 2-chloro-3-methylbutane and 1-chloro-3-methylbutane (4). 2,2-Dimethylpropane skeleton: 1-chloro-2,2-dimethylpropane (1). That is 8 constitutional isomers. Three of them have a stereocentre: 2-chloropentane, 1-chloro-2-methylbutane and 2-chloro-3-methylbutane, each giving a pair of enantiomers. 3-Chloropentane is achiral (two ethyl groups). Total = 8 + 3 = 11.