Which of the following reagents react differently with HCHO, `CH_(3)CHO` and `CH_(3)COCH_(3)` ?

Options

A. HCN
B. `NH_(2)-NH_(2)`
C. `NH_(2)OH`
D. `NH_(3)`

Answer

To determine which of the given reagents reacts differently with formaldehyde (HCHO), acetaldehyde (CH₃CHO), and acetone (CH₃COCH₃), we will analyze the reactions of each reagent with these compounds.

### Step-by-Step Solution:

1. **Identify the Reagents:**
The reagents provided are:
- Hydrogen cyanide (HCN)
- Hydrazine (N₂H₄)
- Ammonium hydroxide (NH₄OH)
- Ammonia (NH₃)

2. **Analyze the Reaction with Hydrogen Cyanide (HCN):**
- HCN reacts with carbonyl compounds (aldehydes and ketones) through nucleophilic addition.
- All three compounds (HCHO, CH₃CHO, CH₃COCH₃) will react similarly with HCN, forming cyanohydrins.
- **Conclusion:** HCN does not react differently with these compounds.

3. **Analyze the Reaction with Hydrazine (N₂H₄):**
- Hydrazine reacts with carbonyl compounds to form hydrazones through a condensation reaction.
- Again, all three compounds will react similarly with hydrazine.
- **Conclusion:** Hydrazine does not react differently with these compounds.

4. **Analyze the Reaction with Ammonium Hydroxide (NH₄OH):**
- Ammonium hydroxide also reacts with carbonyl compounds to form similar products through a condensation mechanism.
- All three compounds will react similarly with ammonium hydroxide.
- **Conclusion:** Ammonium hydroxide does not react differently with these compounds.

5. **Analyze the Reaction with Ammonia (NH₃):**
- Ammonia reacts differently with each of the three compounds:
- **Formaldehyde (HCHO):** Reacts with ammonia to form hexamethylene tetraamine (CH₂)₆N₄ + 6 H₂O.
- **Acetaldehyde (CH₃CHO):** Reacts with ammonia to form an imine (CH₃CH=NH).
- **Acetone (CH₃COCH₃):** Reacts with ammonia to form diacetoamine (CH₃)₂C(NH₂)CH₂COCH₃.
- **Conclusion:** Ammonia reacts differently with all three compounds.

### Final Conclusion:
Among the given reagents, **only ammonia (NH₃)** reacts differently with formaldehyde, acetaldehyde, and acetone.