Question: What is the standard enthalpy change of a reaction (ΔH°) at standard conditions?

Options:

1. 1 atm and 25°C
2. 1 atm and 0°C
3. 2 atm and 25°C
4. 1 atm and 100°C

Correct Answer: 1 atm and 25°C

Solution:

Standard enthalpy change (ΔH°) is measured at standard conditions, which are defined as 1 atm pressure and 25°C (298 K).