Which of the following can decolourise bromine water solution?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds can decolorize bromine water, we need to understand the conditions under which bromine water changes color. Bromine water is typically orange to red in color, and it decolorizes when it reacts with compounds that contain double bonds (alkenes) or certain aromatic compounds that can undergo electrophilic substitution.

### Step-by-Step Solution:

1. **Understanding Bromine Water**:
- Bromine water is orange to red in color. When it reacts with compounds containing double bonds, the color changes to colorless (decolorizes). This indicates the presence of alkenes or certain aromatic compounds.

2. **Identifying the Compounds**:
- We need to analyze each compound provided in the options to check for the presence of double bonds or functional groups that can react with bromine water.

3. **Analyzing Compound A (Phenol)**:
- Phenol has a hydroxyl (-OH) group and a benzene ring. The -OH group activates the ring towards electrophilic substitution.
- Since phenol can react with bromine water, it will decolorize the solution, changing it from orange to colorless.

4. **Analyzing Compound B**:
- Similar to phenol, if this compound also contains a double bond and an -OH group, it will also activate the ring for electrophilic substitution.
- Therefore, this compound will also decolorize bromine water.

5. **Analyzing Compound C**:
- This compound has both an -OH group and a sulfonic acid (-SO3H) group. The -OH group activates the ring, while the -SO3H group deactivates it.
- However, the presence of the double bond means it can still react with bromine water and will decolorize it.

6. **Analyzing Compound D**:
- This compound contains a carboxylic acid group (-COOH) and an -OH group. The -OH group can activate the ring towards electrophilic substitution.
- Thus, this compound will also decolorize bromine water.

7. **Conclusion**:
- All the compounds analyzed (A, B, C, and D) can decolorize bromine water due to the presence of double bonds or reactive functional groups.

### Final Answer:
All the given compounds (A, B, C, and D) can decolorize bromine water.