Which test is used to distinguish aldehydes from Ketones?

Options

A. Tollen's test
B. Fehling's test
C. Both (A) & (B)
D. None of the above

Answer

To determine which test is used to distinguish aldehydes from ketones, we can analyze the characteristics of both functional groups and the specific tests mentioned.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- Aldehydes have the functional group -CHO (carbonyl group at the end of the carbon chain).
- Ketones have the functional group -C(=O)- (carbonyl group within the carbon chain).

**Hint**: Remember the structural difference between aldehydes and ketones; aldehydes have a hydrogen atom attached to the carbonyl carbon, while ketones have two carbon groups attached.

2. **Understand Tollens' Test**:
- Tollens' test involves the use of ammonical silver nitrate (Tollens' reagent).
- Aldehydes can reduce silver ions to metallic silver, resulting in a silver mirror on the test container. Ketones do not react with this reagent.

**Hint**: Recall that Tollens' test is specific for aldehydes due to their ability to be oxidized.

3. **Understand Fehling's Test**:
- Fehling's test uses Fehling's solution, which consists of two solutions (Fehling A: CuSO4 solution and Fehling B: sodium potassium tartrate).
- Aldehydes reduce the blue copper(II) ions (Cu²⁺) to red copper(I) oxide (Cu₂O), while ketones do not produce this reaction.

**Hint**: Remember that the formation of a red precipitate indicates a positive test for aldehydes.

4. **Conclusion**:
- Both Tollens' test and Fehling's test are used to distinguish aldehydes from ketones. Since both tests yield positive results for aldehydes and negative for ketones, they can be used effectively for differentiation.

**Final Answer**: The tests used to distinguish aldehydes from ketones are both A (Tollens' test) and B (Fehling's test).

### Summary:
- **Tollens' Test**: Positive for aldehydes (silver mirror formation).
- **Fehling's Test**: Positive for aldehydes (red precipitate formation).
- **Final Answer**: Both A and B.