`CH_(3)CHO and C_(6)H_(5)CH_(2)CHO` can be distinguished chemically by

Options

A. Benedict's test
B. Iodoform test
C. Tollen's reagent test
D. Fehling's 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: Understand the Compounds
- **CH₃CHO (Acetaldehyde)**: This is a simple aldehyde with a methyl group attached to the carbonyl carbon.
- **C₆H₅CH₂CHO (Benzaldehyde)**: This is an aromatic aldehyde with a phenyl group attached to the carbonyl carbon.

### Step 2: Identify the Test
The iodoform test is used to identify methyl ketones and certain aldehydes that can be oxidized to methyl ketones. In this case, we will apply the iodoform test to distinguish between the two aldehydes.

### Step 3: Perform the Iodoform Test
1. **Reagents Required**: Sodium hydroxide (NaOH) and iodine (I₂).
2. **Reaction with Acetaldehyde**:
- When CH₃CHO is treated with NaOH and I₂, it undergoes a reaction to form iodoform (CHI₃), which is a yellow precipitate.
- The reaction can be summarized as:
\[ CH₃CHO + 3I₂ + 4NaOH \rightarrow CHI₃ + HCOONa + 3NaI + 3H₂O \]
- The formation of a yellow precipitate indicates a positive result for the iodoform test.

3. **Reaction with Benzaldehyde**:
- When C₆H₅CH₂CHO is treated with the same reagents (NaOH and I₂), it does not react to form iodoform.
- Therefore, there will be no yellow precipitate formed.

### Step 4: Conclusion
- The formation of a yellow precipitate indicates the presence of acetaldehyde (CH₃CHO), while the absence of a precipitate indicates the presence of benzaldehyde (C₆H₅CH₂CHO).
- Thus, the iodoform test can be used to distinguish between these two compounds.

### Final Answer
**CH₃CHO and C₆H₅CH₂CHO can be distinguished chemically by the iodoform test.**

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