Ideal Gas Equation and Real Gases – Rankers Physics

Thermodynamics: Practice Problem & Solution

Assertion (A): State variables (P, V and T) of any gas at low densities obey the equation \( PV = nRT \). Reason (R): Real gases are good approximation of an ideal gas at low density.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Thermodynamics. Understanding the underlying formula is key to arriving at the correct answer below:

The ideal gas equation \( PV = nRT \) describes the behavior of an ideal gas. Real gases approximate ideal gas behavior at low densities (and high temperatures) because intermolecular forces become negligible and the volume of gas molecules is tiny compared to the total volume.

Thus, Assertion (A) is true, and Reason (R) is true. Reason (R) directly explains why real gases obey the ideal gas equation at low densities. Therefore, (R) is the correct explanation of (A).

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