Chemistry-Enthalpy

NEET Chemistry Enthalpy MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Which of the following statements about standard molar enthalpy of formation (∆fH°) is correct?

A

The standard molar enthalpy of formation is defined as the enthalpy change when one mole of a compound is formed from its elements in their most stable states.

B

The standard molar enthalpy of formation is always negative for all compounds, indicating that energy is released in all formation reactions.

C

The reference state of an element is its least stable state at 25°C and 1 bar pressure.

D

Mean bond enthalpies are calculated from the enthalpy changes of formation of compounds only at high temperatures.

Correct Answer

Option A

Detailed Explanation

The standard molar enthalpy of formation (∆fH°) is defined as the enthalpy change when one mole of a compound is formed from its elements in their most stable states of aggregation, as stated in the NCERT context.

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