Question

 How many structural isomers can you draw for pentane?

Answer 1

Three structural isomers are possible for pentane.

1) \[\ce{CH3 - CH2 - CH2 - CH2 - CH3}\]

2)

\begin{array}{cc}\
\ce{CH3 - CH2 - CH - CH3}\\
\phantom{......}|\\
\phantom{........}\ce{CH3}
\end{array}

3) 

\begin{array}{cc}\
\phantom{..}\ce{CH3}\\
|\\
\ce{CH3 - C - CH3}\\
|\\
\phantom{...}\ce{CH3}\\
\end{array}