Which equation has an enthalpy change that is accurately described as an enthalpy change of formation?
- A$\text{C}(g) + \text{O}_2(g) \rightarrow \text{CO}_2(g)$
- B$\text{C}(s) + \tfrac{1}{2}\text{O}_2(g) \rightarrow \text{CO}(g)$
- C$2\text{N}(g) + 4\text{O}(g) \rightarrow \text{N}_2\text{O}_4(g)$
- D$2\text{NO}(g) + \text{O}_2(g) \rightarrow 2\text{NO}_2(g)$