`CH_3CHO` and `C_6H_5CH_2CHO` can be distinguished chemically by

Options

A. Benedict test
B. Iodoform test
C. Tollen’s reagent test
D. Fehling solution test

Explanation

To distinguish between `CH₃CHO` (acetaldehyde) and `C₆H₅CH₂CHO` (benzaldehyde), we can use the Iodoform test. Here’s a step-by-step solution:

### Step 1: Understanding the Compounds
- **Acetaldehyde (CH₃CHO)**: This is an aldehyde with a methyl group attached to the carbonyl carbon.
- **Benzaldehyde (C₆H₅CH₂CHO)**: This is an aldehyde with a phenyl group attached to the carbonyl carbon.

### Step 2: Iodoform Test
- The Iodoform test is a chemical test used to identify the presence of a methyl ketone or a compound that can be oxidized to a methyl ketone.

### Step 3: Performing the Iodoform Test
1. **Take a sample of each compound**: Prepare two test tubes, one with acetaldehyde and the other with benzaldehyde.
2. **Add Iodine and Sodium Hydroxide**: To each test tube, add iodine solution and sodium hydroxide (NaOH).
3. **Observe the Reaction**:
- **Acetaldehyde**: When acetaldehyde is treated with iodine and NaOH, it will react to form iodoform (CHI₃), which will precipitate as a yellow solid.
- **Benzaldehyde**: Benzaldehyde does not have a methyl group adjacent to the carbonyl carbon and will not react to form iodoform. Thus, no yellow precipitate will form.

### Step 4: Conclusion
- The formation of a yellow precipitate in the test tube with acetaldehyde indicates a positive Iodoform test, while the absence of precipitate in the test tube with benzaldehyde indicates a negative result. Therefore, these two compounds can be distinguished by the Iodoform test.

### Final Answer
`CH₃CHO` can be distinguished from `C₆H₅CH₂CHO` by the Iodoform test, where `CH₃CHO` gives a yellow precipitate while `C₆H₅CH₂CHO` does not.

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