Question

Assertion(A): In the dissociation of $PC{l}_5$ at constant pressure and temperature addition of helium at equilibrum increases the dissociation of $PC{l}_5$.
Reason(R): Helium removes $C{l}_2$ from the field of action.

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

When inert gas such as helium is added at constant pressure, the equilibrium will shift in the direction in which there is increase in the number of moles of gases. Thus the equilibrium for the dissociation of $PC{l}_5$ will shift to right as the number of moles increases from 1 to 2.