Question

The gases which strictly follow the general equation (PV=nRT) are called ideal perfect gases. Actually, there is no gas which is perfect or ideal. A real gas is one which actually exists whether it obeys gas law strictly or not. Under ordinary conditions only those gases behave as ideal or perfect gas which has low boiling points such as nitrogen, hydrogen etc . The most easily liquefiable and highly soluble gases such as ammonia, carbon dioxide, sulphur dioxide show large deviations.
A very convenient method for studying deviation of real gases from ideal behavior is through a compressibility factor (Z).
$Z = \dfrac{{pV}}{{nRT}}$
i).$Z = 1$, for ideal gases.
ii).$Z \ne 1$, for real gases.
The units of compressibility factor are:
A) $atm{\text{ }}{L^{ - 1}}$
B) $at{m^{ - 1}}$
C) $L$
D) unitless

Answer 1

As we know that an ideal gas follows the law which states that pressure and volume is directly proportional to the temperature and number of moles. The gas which does not follow ideal gas law is known as real gases. Under ordinary conditions only those gases behave as ideal or perfect gas which has low boiling points such as nitrogen, hydrogen etc .

Complete answer:
The compressibility factor is a correction factor that describes the deviation of real gas from ideal gas behavior.
$Z = \dfrac{{pV}}{{nRT}}$
Where p is the pressure, n number of moles of gas, T is the absolute temperature and R is the gas constant. For ideal gas the compressibility factor is per definition.
The gases which strictly follow the general equation (PV=nRT) are called ideal perfect gases. Actually, there is no gas which is perfect or ideal. A real gas is one which actually exists whether it obeys gas law strictly or not. Under ordinary conditions only those gases behave as ideal or perfect gas which has low boiling points such as nitrogen, hydrogen etc . The most easily liquefiable and highly soluble gases such as ammonia, carbon dioxide, sulphur dioxide show large deviations.
Answer- The unit of compressibility factor is unit less.

Note:
We have to know that the value generally increases with pressure and decreases with temperature. At high pressures molecules are colliding more often. A very convenient method for studying deviation of real gases from ideal behavior is through a compressibility factor (Z).
$Z = \dfrac{{pV}}{{nRT}}$
i).$Z = 1$, for ideal gases.
ii).$Z \ne 1$, for real gases.