Question

Any gas shows maximum deviation from ideal behaviour at:
A. $0{}^\circ \text{C}$ and 1 atmospheric pressure
B. $\text{100}{}^\circ \text{C}$ and 2 atmospheric pressure
C. $\text{-100}{}^\circ \text{C}$ and 5 atmospheric pressure
D. $\text{500}{}^\circ \text{C}$ and 1 atmospheric pressure.

Answer 1

Hint: Real gas behaves as an ideal gas when the temperature of a gas is high, but the pressure of gas should be low. Ideal gas follows the gas law under all the conditions of temperature and pressure. The reverse in the condition will cause deviation.

Complete answer:
- In the given question, we have to identify the suitable condition for the deviation of real gas from the ideal behaviour.
- As we know that real gas is those gases which do not follow gas law and also they occupy proper space in the environment and can interact with other molecules.
- Whereas ideal gas are those gases which follow gas law and they have a negligible volume to occupy the space.
- So, we know that the real gas can behave like the ideal gas only under certain conditions such as high temperature with low pressure of the gas.
- Now, when these conditions of the gas are reversed, that is the gas has a low temperature and high pressure then the real gas will deviate from the ideal gas.
- Now, the real gas will not behave like ideal gas.
So, among the given options, option C has the minimum temperature i.e. $\text{-100}{}^\circ \text{C}$ and the highest pressure of 5 atmospheres.
- Whereas in other options the value of temperature is comparatively high and pressure is low.

Therefore, option C is the correct answer.

Note: The deviation of the real gas from the ideal gas can be expressed by the compressibility factor which is denoted by 'Z'. If the value of Z is negative, then it is a negative deviation whereas if Z is positive, then it is a positive deviation.