How many diffenrent alkenes can be hydrogenated to form `2`-methylbutane.

Answer

3

Explanation

Alkenes must have the same skeletal arrangement as the alkanes as hydrogenation only converts the double bond into single bonds:
`C-underset(C )underset(|)C-C-C`
There are three different positions for the double bond, hence the three different alkenes:
`CH_(3)underset(CH_(3))underset(|)(CH)CH=CH_(2)CH_(3)underset(CH_(3))underset(|)C=C CH_(3) CH_(2)=underset(CH_(3))underset(|)C-CH_(2)CH_(3)`