Under which conditions does a real gas show maximum deviation from ideal gas behavior?

Between $NH_3$ and $N_2$,which one has a higher value of $(i) \ a$ and which one has a higher value of $(ii) \ b$? (Where $a$ and $b$ are van der Waals constants.)

What are the corrections made to the pressure and volume of real gases compared to ideal gases?

Consider the following table:

Gas	$a / (kPa \cdot dm^6 \cdot mol^{-2})$	$b / (dm^3 \cdot mol^{-1})$
$A$	$642.32$	$0.05196$
$B$	$155.21$	$0.04136$
$C$	$431.91$	$0.05196$
$D$	$155.21$	$0.4382$

$a$ and $b$ are van der Waals constants. The correct statement about the gases is:

The pressure of a van der Waals gas is less than the pressure of an ideal gas because of

$A$ certain quantity of real gas occupies a volume of $0.15 \ dm^3$ at $100 \ atm$ and $500 \ K$ when its compressibility factor is $1.07$. Its volume at $300 \ atm$ and $300 \ K$ (when its compressibility factor is $1.4$) is $........ \times 10^{-4} \ dm^3$ (Nearest integer).