(A) : Gases do not liquefy above their critical temperature, even on applying high pressure
(R) : Above critical temperature, the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape due to high speed.

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(A) is true but (R) is false

Both (A) and (R) are correct and (R) is the correct explanation of (A)

Both (A) and (R) are false

Both (A) and (R) are correct but (R) is not the correct explanation of (A)

answer is A.

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Detailed Solution

The critical temperature of a gas is the temperature above which it cannot be liquefied, regardless of the pressure applied to it.
This is because, at the critical temperature, the gas is in a state where its density is too low and its kinetic energy is too high for the intermolecular forces to hold the gas molecules together.
At temperatures above the critical temperature, the kinetic energy of the gas molecules is so high that the intermolecular forces of attraction are not strong enough to keep the molecules together.
The molecules move too quickly and tend to escape from each other due to their high speed.
This means that no matter how much pressure is applied to the gas, the intermolecular forces are not strong enough to cause the gas to liquefy.
Therefore, statement (R) correctly explains why gases do not liquefy above their critical temperature.

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