Select from the list the gas that matches the description given in each case: [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne]
This gas when treated with potassium permanganate changes its colour from pink to yellow

Explanation

To solve the question, we need to identify which gas from the given list changes the color of potassium permanganate from pink to yellow when treated with it.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- Potassium permanganate (KMnO4) is a strong oxidizing agent and is purple/pink in color in its acidic solution.
- When it reacts with certain substances, it can change color, often indicating a redox reaction.

...