Question

Van der Waals' constants for three different gases are given :

Gases	$a$	$b$
$X$	$3.0$	$0.025$
$Y$	$10.0$	$0.030$
$Z$	$6.0$	$0.035$

Which is correct?

• A. Maximum critical temperature $-Y$
• B. Most ideal behaviour $-X$
• C. Maximum molecular volume $-Z$
• D. All are correct

Answer 1

The correct option is D All are correct

All the statements are correct.

(A) Maximum critical temperature −Y :

Y has maximum value of the van der Waals' constant 'a'. It represents maximum extent of inter-molecular attractive forces. This results in maximum critical temperature.
(B) Most ideal behavior −X :

X has lowest values of the van der Waals' constants 'a' and 'b'. This refers to least deviation from ideal behaviour.
(C) Maximum molecular volume −Z :

Z has highest value of the van der Waals' constant 'b'.

Therefore, the correct option is D.