De-chlorination is the process of removing chlorine from water. Chlorine is commonly used as a disinfectant in water treatment, but it can have adverse effects on certain industrial processes or aquatic environments. Several chemical compounds can be used for de-chlorination, but in this case, the correct answer is option 'D': sulphur dioxide.

Sulphur dioxide (SO2) is a commonly used de-chlorination agent due to its effectiveness in removing chlorine from water. It reacts with chlorine to form hydrochloric acid (HCl) and sulphuric acid (H2SO4), both of which are water-soluble and can be easily removed from the water.

Here is a detailed explanation of why sulphur dioxide can be used for de-chlorination:

1. Sulphur Dioxide (SO2):
- Sulphur dioxide is a colorless gas with a pungent odor.
- It is readily soluble in water, forming sulphurous acid (H2SO3).
- Sulphur dioxide can react with chlorine gas (Cl2) to form hydrochloric acid (HCl) and sulphuric acid (H2SO4).

2. Reaction with Chlorine:
- When sulphur dioxide gas is introduced into water containing chlorine, it reacts with the chlorine to form hydrochloric acid and sulphuric acid.
- The reaction can be represented as follows:
SO2 + Cl2 + H2O → HCl + H2SO4

3. Removal of Acids:
- Both hydrochloric acid and sulphuric acid formed during the reaction are water-soluble and can be easily removed from the water.
- The de-chlorinated water can then be used for various purposes without the harmful effects of chlorine.

4. Advantages of Sulphur Dioxide:
- Sulphur dioxide is readily available and relatively inexpensive.
- It is a strong de-chlorination agent, capable of efficiently removing chlorine from water.
- The reaction between sulphur dioxide and chlorine is relatively rapid.

5. Other De-chlorination Agents:
- While sulphur dioxide is an effective de-chlorination agent, other compounds can also be used.
- Carbon dioxide (option 'A') is not commonly used for de-chlorination, as it does not react directly with chlorine.
- Chloramines (option 'B') are actually a combination of chlorine and ammonia, so they would not be suitable for de-chlorination.
- Bleaching powder (option 'C'), also known as calcium hypochlorite, is actually a source of chlorine and not a de-chlorination agent.

In conclusion, sulphur dioxide is a suitable chemical compound for de-chlorination of water due to its ability to react with chlorine and form water-soluble acids.