Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: If the average kinetic energy of $H_2$ and $O_2$ molecules, kept in two different sized containers are same, then their temperatures will be same.
Reason R: The r.m.s. speed of $H_2$ and $O_2$ molecules are same at same temperature.
Choose the correct answer from the options given below

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

Answer 1

The Correct Option is C

Step 1: Check assertion
Average kinetic energy is \[ K=\frac{3}{2}kT \] Since it depends only on temperature, same average kinetic energy means same temperature. Hence Assertion A is true. Step 2: Check reason
RMS speed is \[ v_{rms}=\sqrt{\frac{3RT}{M}} \] It depends on molar mass $M$. Since \[ M(H_2)\ne M(O_2) \] their RMS speeds are not same at same temperature. Hence Reason R is false. Final Answer: \[ \boxed{\text{(C) A is true but R is false}} \]