The enthalpy change at 298 K of the reaction $H_2O_2(l) \longrightarrow H_2O (l) + \frac{1}{2} O_2 (g)$ is -23.5 kcal $mol^{-1}$ and enthalpy of formation of $H_2O_2(l)$ is -44.8 kcal $mol^{-1}$. The enthalpy of formation of $H_2O(l)$ is

Question

(a) -68.3 kcal $mol^{-1}$
(b) 68.3 kcal $mol^{-1}$
(c) -91.8 kcal $mol^{-1}$
(d) 91.8 kcal $mol^{-1}$