Which of the following is used to detect aldehydes

Options

A. Millon's test
B. Tollen's reagent
C. Neutral ferric chloride solution
D. Molisch's test

Explanation

To determine which reagent is used to detect aldehydes, we can follow these steps:

### Step 1: Understand the nature of aldehydes
Aldehydes are organic compounds that contain a carbonyl group (C=O) at the end of a carbon chain. They can be oxidized to carboxylic acids.

### Step 2: Identify common reagents for detecting aldehydes
Several reagents can be used to detect aldehydes, including:
- Tollens' reagent
- Benedict's solution
- Mercury(II) chloride (HgCl2)
- Schiff's reagent
- Fehling's solution

### Step 3: Analyze the reagents
- **Tollens' reagent**: This is a silver nitrate solution in ammonia. It reacts with aldehydes to produce a silver mirror, indicating the presence of an aldehyde.
- **Benedict's solution**: This reagent can detect both aldehydes and reducing sugars, changing color when aldehydes are present.
- **Mercury(II) chloride (HgCl2)**: This reagent can also react with aldehydes but is less commonly used for detection.
- **Schiff's reagent**: This reagent turns pink in the presence of aldehydes.
- **Fehling's solution**: Similar to Benedict's, it can detect aldehydes by forming a brick-red precipitate.

### Step 4: Conclusion
Among the reagents mentioned, **Tollens' reagent** is specifically known for its ability to differentiate aldehydes from ketones, as it reacts with aldehydes but not with ketones.

### Final Answer
**Tollens' reagent is used to detect aldehydes.**

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