Question

How many minimum carbons required for Chain isomerism and Position isomerism in alkenes?

Answer 1

Minimum $4$ carbon atoms are required to show position and chain isomerism in alkenes.

For example: $But-1-ene$ $C{H}_3-C{H}_2-CH=C{H}_2$ {position isomerism}

$But-2-ene$ $C{H}_3-CH=CH-C{H}_3$ {position isomerism}