Molecular Motion and Absolute Zero – Rankers Physics

Kinetic Theory of Gases: Practice Problem & Solution

Assertion (A): All molecular motion ceases at \(-273.15^{\circ}C\). Reason (R): Temperature \(0K\) cannot be attained.  
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

Solution Explained:

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

Assertion (A) is true. \(-273.15^{circ}C\) is equivalent to \(0 K\), at which point theoretical classical molecular motion ceases. Reason (R) is true, as the Third Law of Thermodynamics states that absolute zero cannot be reached. However, R describes the attainability of \(0 K\), not the phenomenon of molecular motion ceasing at that temperature. Thus, R is not the correct explanation of A.

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