Molecular Energy and Temperature – Rankers Physics

Kinetic Theory of Gases: Practice Problem & Solution

Assertion (A): Energy of molecules increase on increasing the temperature. Reason (R): All substances expand on increasing the temperature.  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) 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; average kinetic energy of molecules is directly proportional to absolute temperature. Reason (R) is false because some substances, like water between \(0^{circ}text{C}\) and \(4^{circ}text{C}\,) contract upon heating. Thus, (A) is true and (R) is false.

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Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): Two metallic spheres of same size, one of copper and the other of aluminium, heated to the same temperature, will cool at the same rate when they are suspended in the same enclosure. Reason (R): The rate of cooling of a body depends only on the excess of temperature of the body over the surroundings.  
2. A cup of coffee cools from \(90^\circ\text{C}\) to \(80^\circ\text{C}\) in \(t\) minutes, when the room temperature is \(20^\circ\text{C}\). The time taken by a similar cup of coffee to cool from \(80^\circ\text{C}\) to \(60^\circ\text{C}\) at a room temperature same at \(20^\circ\text{C}\) is
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