Q58 / 180 · AIIMS 2002 · Chemistry

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.

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

Solution

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 $$ \Delta E=E_f-E_i $$

Hence, the correct answer is option: 'A'.

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