Question

Assertion : Absolute values of internal energy of substances can not be determined.
Reason : It is impossible to determine exact values of constituent energies of the substances.

• A. If both assertion and reason are true and reason is a correct explanation of the assertion
• B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
• C. If the assertion is true but the reason is false
• D. If both the assertion and reason are false

Answer 1

Answer: (A)

Internal energy is given by:

$E=E_{\text{translational }}+E_{\text{rotaional }}+E_{\text{vibrational }}+E_{\text{bonding }}+E_{\text{electronic }}$

Accurate measurement of some forms of energy which contribute to the absolute value of internal energy for a given substance in a given state is impossible. So difference of the initial state and final state is calculated and is denoted by

$\Delta E=E_f-E_i$