Question

\( \text{NH}_4 \text{Cl} \) is heated in a test tube. Vapours are brought in contact with red litmus paper, which changes it to blue and then to red. It is because of

• A. formation of \( \text{NH}_3 \) and HCl
• B. formation of \( \text{N}_2 \) and HCl
• C. greater diffusion of \( \text{NH}_3 \) than HCl
• D. greater diffusion of HCl than \( \text{NH}_3 \)

Hint:

Ammonia diffuses faster than HCl due to its lower molar mass, which is why it affects the litmus paper first.

Answer 1

The Correct Option is C

Step 1: Analyzing the reaction.
When \( \text{NH}_4 \text{Cl} \) is heated, it dissociates into ammonia \( \text{NH}_3 \) and HCl. The ammonia diffuses faster than HCl, which changes the litmus paper.

Step 2: Conclusion.
The correct answer is that the ammonia diffuses faster than HCl, corresponding to option (3).