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

An Ideal gas is defined as one in which collisions between atoms or molecules are elastic and there is no intermolecular force of attraction. Ideal gas is hypothetical gas.

Complete step by step answer:
Generally, all gases are non - ideal.
The gas consists of a large number of molecules, which are random in motion and obeys Newton’s law of motion.
The volume of gas is negligible compared to volume occupied by the gas.
There will be no force of attraction between molecules of gas.
But no gas behaves ideally. It is theoretical gas and composed of many randomly moving particles having less interaction.
At STP [Standard temperature and pressure] air and most pure gases will behave closely to an ideal gas.
At relatively low pressure, gaseous molecules do not have attraction for one another because they are far apart from each other.
At high pressure intermolecular attraction is more due to small volume.
At high temperature Kinetic energy of gaseous molecules is very high so they move very fast and remain far apart from each other.
At low temperature kinetic energy is less and molecules come closer to one another attraction also increases. So gases do not behave ideally.
Thus, a real gas behaves as ideal gas, as long as temperature is high and the pressure is low.

So, the correct answer is “Option C”.

Note:
The gases which do not behave ideally are real gases or non-ideal gases. These gases occupy space and have interaction. Ideal gases obey gas laws.