Answer:

Correct option is

B

Hydrogen and HELIUM are more compressible than ideal gases for all values of pressure.

D

The compressibility factor of real gases is independent of temperature.

At high pressure, the gas molecules come close to each other and the empty SPACE between the molecules is reduced to some extent. Therefore the gas becomes less compressible at these higher pressures.

From real gas equation,

(P+

nV

2

a

)(V−nb)=RT

At high pressure the factor

nV

2

a

is negligible COMPARE to P. Thus the equation becomes,

P(V−nb)=RT⇒Z=

RT

P(V−nb)

>1

Hence at high pressure, all real gases are less compressible than ideal gases.

Option A is correct.

He and H

2

are less compressible than ideal gas because in case of He and H

2

the compressibility factor is Z>1. Only for low pressure and high volume the given statement is favourable. Hence option B is incorrect.

He and H

2

are exceptional cases due to their small SIZE, the intermolecular attraction force are negligible. Therefore even at low pressure the volume factor is high so the compressibility factor Z>1. Option C is correct.

The compressibility factor, Z∝

T

1

. Higher the temperature lower the deviation from ideal gas, Z→1. Option D is incorrect.

Option B and D are the answer.