Question

A gas described by van der Waals equation :

• A. Behaves similar to an ideal gas in the limit of large molar volumes
• B. Behaves similar to an ideal gas is in limit of large pressures
• C. Is characterised by van der Waals coefficients that are dependent on the identity of the gas but are independent of the temperature
• D. Has internal pressure due to the intermolecular forces between the molecules

Answer 1

Answer: (A), (C), (D)

The correct options are
A Behaves similar to an ideal gas in the limit of large molar volumes
C Is characterised by van der Waals coefficients that are dependent on the identity of the gas but are independent of the temperature
D Has internal pressure due to the intermolecular forces between the molecules

Van der waals equation is
$(p+\frac{n^{2}a}{V^2})(V-nb)=nRT\text{(for n moles of a gas)}$
$a,b$ are Van der waal's constant
The ideal gas equation is $PV=nRT\text{(for n moles of a gas)}$
Where, $P$ is pressure exerted by ideal gas and $V$ is volume occupied by ideal gas .
In Van der waals equation the term $(p+\frac{n^{2}a}{V^2})$ represents the pressure excerted by the gas and $(V-nb)$ the volume occupied by the gas. At low pressure, when the gas occoupies large volume the intermolecular distance between gaseous molecules is quite large and in such case there is no significant role played by to forces and thus the gas behaves like an ideal gas thus (a) is correct.
Under high pressure the intermolecular distance decreases and the intermolecular forces play a significant role and the gas shows a devation from ideal behaviour. Thus (b) is not correct.
$a,b$ i.e., the vander Waals coefficients defined on the nature of gas and are independent of temperature so (c) is correct.

$\frac{n^{2}a}{V^2}$ represents the internal pressure due to attractive intermolecular forces.
Hence, the correct answer is $a,c,d$