Question

A gas can be liquefied, if Van der Waals:

• A. forces of attraction are low under ordinary conditions
• B. forces of attraction are high under ordinary conditions
• C. forces of attraction are zero under ordinary conditions
• D. forces of attraction either high or low under ordinary conditions

Answer 1

Answer: (A), (B), (D)

forces of attraction are low under ordinary conditions
forces of attraction are high under ordinary conditions
forces of attraction either high or low under ordinary conditions

The constants 'a' and 'b': Van der Waals constant for attraction 'a' and volume 'b' are characteristic constants for a given gas.
(i)The 'a' values for a given gas are a measure of intermolecular forces of attraction. More are the intermolecular forces of attraction, more will be the value of a.
(ii)For a given gas van der Waals constant of attraction 'a' is always greater than van der Waals constant of volume 'b'.
(iii)The gas having a higher value of 'a' can be liquefied easily and therefore $H_2$ and He is not liquefied easily.
So gas can be liquefied if forces of attraction either high or low under ordinary conditions.