Answer: Heat absorbed or released.
- A Work done
- B Internal energy change
- C Heat absorbed or released
- D Gibbs energy
Correct answer: C. Heat absorbed or released
Explanation: At constant pressure, ΔH = qp, the heat absorbed or released by the system.
Isothermal expansion follows a gentler curve (heat flows in to keep T constant) while adiabatic expansion drops in pressure more steeply (no heat exchange, so internal energy and temperature fall as the gas does work).
Concept context
Study energy changes in chemical reactions. Understand enthalpy, entropy, Gibbs free energy, and the laws of thermodynamics that decide whether a reaction will occur spontaneously or not.