Question

A gas will approach ideal behavior at:
A: Low temperature and low pressure
B: Low temperature and high pressure
C: High temperature and low pressure
D: High temperature and high pressure

Answer 1

Ideal gas is a theoretical gas. This gas is composed of randomly moving particles of gas. There is no force between the particles of ideal gas. Ideal gas equation relates the relation of pressure and volume of a gas with number of moles and temperature of gas.

Complete step by step answer:
An ideal gas is a gas that obeys the gas laws at all temperature and pressures. There is no force of attraction or repulsion between the particles of ideal gas and the volume of particles is negligible. But in actuality there is no such condition possible. That is why ideal gas is a theoretical gas. But some assumptions are made for an ideal gas. These assumptions are as follows:
$1.$ Volume of the particle of gas is very small as compared to volume of gas.
$2.$ Gas consists of a very large number of molecules and these molecules are in random motion.
$3.$ There is no force between the particles of gas except the force due to elastic collision.
When the temperature of gas will be high and pressure of the gas will be low, the gas particles will stay away from each other. Due to which there will be no force between the particles. Also the volume of the gas will be high and the volume of the particles will be negligible for this high volume of gas and this will satisfy the conditions of ideal gas. Therefore, a gas can approach ideal gas at high temperature and low pressure.
Hence, the correct answer is option C.

Note:
Ideal gas models fail at low temperature and high pressure because when the temperature will be low and pressure will be high due to which, the gas molecules will be close to each other and there will be forces of attraction or repulsion. These two conditions violate ideal gas law.