$(i)\,\mathop {\begin{array}{*{20}{c}}
  {\,\,\,\,\,C{H_3}} \\ 
  | \\ 
  {C{H_3} - C - C{H_3}} \\ 
  | \\ 
  {\,\,\,\,\,C{H_3}} 
\end{array}}\limits_{(Neo - pen\tan e)\,(i)} $

$(ii\mathop {)\,\begin{array}{*{20}{c}}
  {C{H_3} - CH - C{H_2} - C{H_3}} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {\,\,\,\,\,C{H_{3\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}}} 
\end{array}}\limits_{(Iso - pen\tan e)\,\,(ii)} $

$(iii)\,\mathop {C{H_3} - C{H_2} - C{H_2} - C{H_2} - C{H_3}}\limits_{(n - pen\tan e)} $