Question

Assertion :At constant temperature, if the pressure of the gas is doubled, the density is also doubled. Reason: At constant temperature and pressure, the molecular mass of gas is directly proportional to the density.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

Ideal gas equation $PV=nRT$

$P=\frac{n}{V}RT$ and we know $\frac{W}{v}=d=$ density

$P=\frac{dRT}{M}$

$\therefore$ if we doubles the pressure then density also becomes doubles to balance the L.H.S and R.H.S

Molecular mass does not depend upon T, P.

Thus, at constant temperature and pressure, the molecular mass of gas is not directly proportional to the density.