Question

Assertion (A): Decrease in free energy causes spontaneous reaction.
Reason (R): Spontaneous reactions are invariable exothermic reactions.

• A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
• B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
• C. Assertion is true but Reason is false.
• D. Both Assertion and Reason are false.

Answer 1

The correct option is C Assertion is true but Reason is false.

$\Delta G=\Delta H-T\Delta S$
For a spontaneous reactions $\Delta G$ should be +ve.
$\therefore \Delta H$ can be either +ve or -ve for a spontaneous reaction.
$\Delta H<T\Delta S$ for a spontaneous reaction.
Decrease in G results in -ve $\Delta G$. Thus, spontaneous.