Which reagent can distinguish between pentanoic acid and pentanamide ?

Options

A. Cold `dil. NaOH`
B. Cold `dil. NaHCO_3`
C. Cold `conc. H_2 SO_4`
D. All

Explanation

To distinguish between pentanoic acid and pentanamide, we can use several reagents that react differently with these two compounds. Let's analyze the situation step by step.

### Step 1: Identify the Structures
- **Pentanoic Acid**: The chemical formula is C5H10O2, and its structure is CH3(CH2)3COOH. It contains a carboxylic acid functional group (-COOH).
- **Pentanamide**: The chemical formula is C5H11NO, and its structure is CH3(CH2)3CONH2. It contains an amide functional group (-CONH2).

### Step 2: Choose the Reagents
We will consider three reagents:
1. Cold dilute NaOH
2. Cold dilute NaHCO3
3. Concentrated H2SO4

### Step 3: Analyze the Reactions
1. **Cold Dilute NaOH**:
- **With Pentanoic Acid**: No reaction occurs.
- **With Pentanamide**: Hydrolysis occurs, producing ammonia (NH3) gas.
- **Conclusion**: This reagent can distinguish between the two compounds.

2. **Cold Dilute NaHCO3**:
- **With Pentanoic Acid**: Reaction occurs, producing carbon dioxide (CO2) gas.
- **With Pentanamide**: No reaction occurs.
- **Conclusion**: This reagent can also distinguish between the two compounds.

3. **Concentrated H2SO4**:
- **With Pentanoic Acid**: No reaction occurs.
- **With Pentanamide**: Hydrolysis occurs, producing ammonia (NH3) gas.
- **Conclusion**: This reagent can also distinguish between the two compounds.

### Step 4: Final Conclusion
All three reagents (cold dilute NaOH, cold dilute NaHCO3, and concentrated H2SO4) can distinguish between pentanoic acid and pentanamide. Therefore, the answer is **all of the above**.

### Final Answer
The reagent that can distinguish between pentanoic acid and pentanamide is **all of the above** (cold dilute NaOH, cold dilute NaHCO3, and concentrated H2SO4).

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