For which of the following gases will the van der Waals constant $'a'$ have the highest value?

At low pressure,the van der Waals equation becomes

Under which conditions does a gas show the greatest deviation from the ideal gas equation $PV = nRT$?

At $300 \ K$,one mole of a gas present in a $10 \ L$ flask exerted a pressure of $2.706 \ atm$. What is its compressibility factor $(Z)$? (Given $R=0.082 \ L \ atm \ mol^{-1} \ K^{-1}$).

When helium gas is allowed to expand into vacuum, a heating effect is observed. The reason for this is (assume $He$ as a non-ideal gas):

$1 \ mol$ of a real gas is kept at a high pressure of $100 \ bar$ at $300 \ K$. If the van der Waals constant $b$ is $0.005 \ L \ mol^{-1}$, what are the values of the compressibility factor $Z$ of the gas and the $\%$ deviation of volume from ideality?

$Z$	$\%$ Deviation