b
Heat supplied at constant pressure $=\mathrm{nC}_{\mathrm{p}} \Delta \mathrm{T}$
Change in internal energy $=\mathrm{nC}_{\mathrm{v}} \Delta \mathrm{T}$
$\therefore$ Fraction $=\frac{C_{v}}{C_{p}}=\frac{1}{\gamma}$
For a non$-$linear triatomic gas $\gamma=\frac{4}{3}$
fraction $=\frac{3}{4}$