Which statement correctly pairs the sign of ΔH with the type of process?

• A. ΔH > 0 Endothermic
• B. ΔH > 0 Exothermic
• C. ΔH < 0 Endothermic
• D. ΔH < 0 Isothermal

Answer: (A)

Enthalpy change (ΔH) tells us how much heat is involved at constant pressure. When a process absorbs heat from the surroundings, the system’s enthalpy increases, giving a positive ΔH. That’s what an endothermic process does. Conversely, when heat is released, ΔH is negative, which describes an exothermic process. Isothermal means the temperature stays the same, which doesn’t by itself fix the sign of ΔH (for an ideal gas, ΔH = nCpΔT, so if the temperature doesn’t change, ΔH would be zero, but this depends on the substance). So the pairing ΔH > 0 with endothermic is the correct one.