$4\mathrm{.}40$ Draw the structure of a hydrocarbon that reacts with only $1$ equivalent of $H_2$ on catalytic hydrogenation and gives only pentanoic acid, $C{H}_{3}C{H}_{2}C{H}_{2}C{H}_{2}C{O}_{2}H,$ on treatment with acidic $KMn{O}_4.$ Write the reactions involved.