Compound X decolourises acidified potassium dechromate to produce an acid with a pH value of 4.5. Which of the following could be the structure of X?

Options

A. `CH_(3)CH_(2)COOH`
B. `CH_(3)CH_(2)CH_(2)OH`
C. `CH_(2)=CH-CH_(3)`
D. `CH_(3)CH_(2)CH_(3)`

Explanation

To solve the problem, we need to analyze the information given about compound X and its reaction with acidified potassium dichromate (K2Cr2O7).

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- Potassium dichromate is a strong oxidizing agent, especially in acidic conditions. It can oxidize alcohols to acids or aldehydes.
- The reaction produces an acid, which has a pH of 4.5. This indicates that the resulting solution is acidic but not strongly acidic (pH < 7).

2. **Identifying Possible Structures for X**:
- Since the reaction involves oxidation and produces an acid, compound X is likely to be an alcohol. Alcohols can be oxidized to carboxylic acids or aldehydes.
- The pH of the resulting acid (4.5) suggests that the acid is not a strong acid (like HCl or H2SO4) but rather a weak acid, which is consistent with a carboxylic acid.

3. **Choosing the Correct Alcohol**:
- The simplest alcohol that can be oxidized to a carboxylic acid is propanol (C3H7OH).
- When propanol (specifically, 1-propanol) is oxidized by potassium dichromate, it forms propanoic acid (C2H5COOH). This acid has a pH that can be around 4.5 in dilute solutions.

4. **Conclusion**:
- Therefore, the structure of compound X is likely to be 1-propanol (C3H8O), as it fits the criteria of being an alcohol that can be oxidized to produce an acid with a pH of 4.5.

### Final Answer:
Compound X is likely to be 1-propanol (C3H8O).