Chemistry - Thermochemistry Question with Solution | TestHub

An endothermic compound has a standard enthalpy of formation, Δ H^°_f, greater than 0.

Let's examine the given compounds:

* NO(g): +90 kJ/mol (endothermic)

* CO_₂(g): -393.5 kJ/mol (exothermic)

* CO(g): -110.5 kJ/mol (exothermic)

* NH_₃(g): -46 kJ/mol (exothermic)

Therefore, NO(g) is the endothermic compound. The answer is (a).