How many structural isomers can you draw for pentane?

Explanation

Three structural isomers are possible for pentane.
(i) `CH_(3)-CH_(2)-CH_(2)-CH_(2)-CH_(3)`
(ii) `CH_(3)-CH_(2)-underset(CH_(3))underset(|)(CH)-CH_(3)`
(iii) `CH_(3)-overset(CH_(3))overset(|)underset(CH_(3))underset(|)C-CH_(3)`