$2.$ $\mathop {C{H_3} - \mathop {\mathop {CH - }\limits_{|\,\,\,\,\,\,\,\,\,} }\limits_{C{H_3}} C{H_2} - C{H_2} - C{H_3}}\limits_{{\rm{2}} - {\rm{methyl}}\,{\rm{pentane}}} $
$3.$ $\mathop {C{H_3} - C{H_2} - \mathop {\mathop {CH}\limits_{|\,\,\,\,\,\,} }\limits_{\,\,\,C{H_3}} - C{H_2} - C{H_3}}\limits_{{\rm{3}} - {\rm{methyl}}\,{\rm{pentane}}} $
$4.$ $\mathop {C{H_3} - \mathop {\mathop {CH - }\limits_{|\,\,\,\,\,\,\,\,\,} }\limits_{C{H_3}} \mathop {\mathop {CH - }\limits_{|\,\,\,\,\,\,\,\,\,} }\limits_{C{H_3}} C{H_3}}\limits_{{\rm{2,3}} - {\rm{Dimethyl}}\,{\rm{butane}}} $
$5.$ $\mathop {C{H_3} - C{H_2} - \mathop {\mathop {CH}\limits_{|\,\,\,\,\,\,} }\limits_{\,\,\,C{H_3}} - C{H_2} - C{H_3}}\limits_{{\rm{3}} - {\rm{methyl}}\,{\rm{pentane}}} $