The van der Waals equation reduces to the ideal gas equation under which of the following conditions?

What is meant by Boyle temperature and Boyle point?

Match the Van der Waals constant $a$ (in $L^2 \cdot bar \cdot mol^{-2}$) for the following gases:

Gas	$a$ value
$1. C_6H_{6(g)}$	$a. 0.217$
$2. C_6H_5CH_{3(g)}$	$b. 5.464$
$3. Ne_{(g)}$	$c. 18.000$
$4. H_2O_{(g)}$	$d. 24.060$

$A$ gas has a compressibility factor of $0.5$ and a molar volume of $0.4 \ dm^3 \ mol^{-1}$ at a temperature of $800 \ K$ and pressure $x \ atm$. If it shows ideal gas behaviour at the same temperature and pressure,the molar volume will be $y \ dm^3 \ mol^{-1}$. The value of $x / y$ is . . . . . .
[Use: Gas constant,$R = 8 \times 10^{-2} \ L \ atm \ K^{-1} \ mol^{-1}$ ]

Under which conditions will a real gas behave most like an ideal gas?

The Van der Waals constant '$a$' for the gases $O_2$,$N_2$,$NH_3$ and $CH_4$ are $1.3$,$1.390$,$4.170$ and $2.253 \ L^2 \ atm \ mol^{-2}$ respectively. The gas which can be most easily liquefied is