For which of the following reactions does = (a) (b) (c)

QUESTION:

For which of the following reactions does \(\Delta H_{r x n}^{\circ}=\Delta H_{f}^{\circ}\)?

(a) \(\mathrm{H}_{2}(\mathrm{g})+\mathrm{S}(\text { rhombic }) \rightarrow \mathrm{H}_{2} \mathrm{S}(\mathrm{g})\)

(b) \(C(\text { diamond })+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})\)

(c) \(H_{2}(g)+C u O(s) \rightarrow H_{2} O(l)+C u(s)\)

(d) \(O(g)+O_{2}(g) \rightarrow O_{3}(g)\)