In a $P$ versus $V$ graph,the horizontal line is found in which region?

Any gas shows maximum deviation from ideal gas behavior at

Assertion : Greater the value of van der Waal's constant $a$,greater is the liquefaction of gas.
Reason : $a$ indirectly measures the magnitude of attractive forces between the molecules.

The pressure of real gases is less than that of ideal gas because of:

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

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

At $S.T.P.$,if the compressibility factor $(Z)$ of a gas is less than $1$,then which of the following is true?