Assertion: The heat absorbed during the isothermal expansion of an ideal gas against vacuum is zero.
Reason: The volume occupied by the molecules of an ideal gas is zero.

Options

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

Answer

B

Explanation

Assertion : Isothermal expansion against vacuum `Delta T= 0 rArr Delta E= 0`
In vacuum `P_("ext")= 0 rArr W= - P_("ext") Delta V= 0`
So q is also equal to zero.
Reason: The volume occupied by the molecules of an ideal gas is zero but this is not the correct explanation for the assertion