A gas ( Molar mass $=280 \mathrm{g}{ \mathrm{mol}}^{-1}$) was burnt in excess ${\mathrm{O}}_2$ in a constant volume calorimeter and during combustion the temperature of calorimeter increased from $298.0 \mathrm{K}$ to $298.45 \mathrm{K}$. If the heat capacity of calorimeter is $2.5 \mathrm{kJ}{ \mathrm{K}}^{-1}$ and enthalpy of combustion of gas is $9 \mathrm{kJ}{ \mathrm{mol}}^{-1}$ then amount of gas burnt is____$\mathrm{g}$.

Hence, the correct answer is 35.