The standard heat of formation in kcal/mol of ${\text{Ba}}^{2+}$ is

Given: standard heat of formation of ${\text{SO}}_4^{2-}$ $io{n}_{\left(aq\right)}$ = $-216$ kcal/mol, standard heat of crystallisation of $BaS{O_4}_{\left(s\right)}=-4.5$ kcal/mol, standard heat of formation of $BaS{O_4}_{\left(s\right)}=-349$ kcal/mol.                         [2025]

Consider the following reaction:  

$2{\text{H}}_{2\left(g\right)}+{\text{O}}_{2\left(g\right)}\to 2{\text{H}}_2{\text{O}}_{\left(g\right)}; {\Delta }_{\mathit{r}}H°=-483.64$ $\text{kJ}$

What is the enthalpy change for decomposition of one mole of water? (Choose the right option.)         [2023]