Question

Assertion: Compressibility factor for hydrogen varies with pressure with positive slope at all pressure.
Reason: Even at low pressure, repulsive forces dominate for hydrogen gas.

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

Answer 1

Answer: (A)

In case of $H$, compressibility factor (Z) increases with pressure. At $273 K , Z>1$, which show that it is difficult to compress the gas as compared to ideal gas. In this case repulsive forces dominate.
Note : For ideal gases, $Z=1$
For real gases $Z \neq 1$
If $Z<1$, negative deviation and the gas is more compressible than expected.
If $Z>1$, positive deviation and the gas is less compressible than expected.