Question

Assertion :The compressibility factor for $H_2$ and $He$ is $[1+\frac{Pb}{RT}]$. Reason: The compressibility factor for $H_2$ and $He$ can be derived from van der Waal's equation.

• 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. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

The compressibility factor for hydrogen and $He$ can be derived from van der Waal's equation which is $[P+\frac{a}{V^2}][V-b]=RT$.
The value of $a$ is very small for hydrogen and helium because they have low molar mass.
Hence, the van der Waal's equation becomes van der Waal's equation.
The expression for the compressibility factor becomes $Z=\frac{PV}{RT}=[1+\frac{Pb}{RT}]$.
Thus, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.