1.
Heat of combustion ΔH∘\Delta H^\circ for C(s)C(s), H2(g)H_2(g) and CH4(g)CH_4(g) are −94-94, −68-68 and −213-213 kcal mol−1^{-1} respectively. Then ΔH∘\Delta H^\circ for C(s)+2H2(g)→CH4(g)C(s) + 2H_2(g) \to CH_4(g) is: