OnlineCBT
Chemistry · THERMODYNAMICS
हिन्दीWhich of the following substances has a standard molar enthalpy of formation (\( \Delta_f H^\ominus \)) equal to zero at 298 K and 1 bar by convention?
Correct answer · Option 1
\( \text{C}(\text{graphite}) \)
Explanation
Graphite is the thermodynamically most stable reference form of elemental carbon at 298 K and 1 bar, so its \( \Delta_f H^\ominus = 0 \), whereas diamond has \( \Delta_f H^\ominus = +1.89\text{ kJ mol}^{-1} \).
