Question

Given below are two statements : One is labelled as Assertion $A$ and the other is labelled as Reason $R$.

Assertion $A$ : When a rod lying freely is heated, no thermal stress is developed in it.

Reason $R$ : On heating, the length of the rod increases.

In the light of the above statements, choose the correct answer from the options given below.

• A. $A$ is true, but $R$ is false.
• B. Both $A$ and $R$ are true, and $R$ is the correct explanation of $A$.
• C. Both $A$ and $R$ are true, but $R$ is NOT the correct explanation of $A$.
• D. $A$ is false, but $R$ is true.

Answer 1

The correct option is C Both $A$ and $R$ are true, but $R$ is NOT the correct explanation of $A$.

If a rod is free, and it is heated, then there is no thermal stress produced in it as there is no external agent to produce stress.

The rod will expand due to an increase in temperature.

So, both $A$ and $R$ are true.

However, $R$ is not the correct explanation of $A$.