Which of the following molecules are expected to exhibit intermolecular H-bonding ?
(I) Acetic acid ((II) o-nitrophenol (III) m-nitrophenol (IV)o-boric acid
Select correct alternate :

Options

A. I, II, III
B. I,II,IV
C. I,III,IV
D. II,III,IV

Answer

To determine which of the given molecules exhibit intermolecular hydrogen bonding, we will analyze each molecule one by one.

### Step 1: Identify the molecules
The molecules given are:
1. Acetic acid (CH₃COOH)
2. o-Nitrophenol (C₆H₄(NO₂)OH)
3. m-Nitrophenol (C₆H₄(NO₂)OH)
4. o-Boric acid (H₃BO₃)

### Step 2: Understand hydrogen bonding
Hydrogen bonding occurs when a hydrogen atom is covalently bonded to a highly electronegative atom (like oxygen, nitrogen, or fluorine) and is attracted to another electronegative atom in a different molecule.

### Step 3: Analyze Acetic Acid
- **Structure**: CH₃COOH has an -OH group.
- **Intermolecular hydrogen bonding**: The hydrogen from the -OH group of one acetic acid molecule can form a hydrogen bond with the oxygen of another acetic acid molecule.
- **Conclusion**: Acetic acid exhibits intermolecular hydrogen bonding.

### Step 4: Analyze o-Nitrophenol
- **Structure**: o-Nitrophenol has an -OH group and a nitro group (NO₂) on the aromatic ring.
- **Intermolecular hydrogen bonding**: The -OH group can form hydrogen bonds with the oxygen of another -OH group from a different o-nitrophenol molecule.
- **Conclusion**: o-Nitrophenol exhibits intermolecular hydrogen bonding.

### Step 5: Analyze m-Nitrophenol
- **Structure**: m-Nitrophenol also has an -OH group but the nitro group is in the meta position.
- **Intermolecular hydrogen bonding**: Similar to o-nitrophenol, the -OH group can form hydrogen bonds with the oxygen of another -OH group from a different m-nitrophenol molecule.
- **Conclusion**: m-Nitrophenol exhibits intermolecular hydrogen bonding.

### Step 6: Analyze o-Boric Acid
- **Structure**: o-Boric acid (H₃BO₃) has multiple -OH groups.
- **Intermolecular hydrogen bonding**: The -OH groups can interact with the -OH groups of other boric acid molecules.
- **Conclusion**: o-Boric acid exhibits intermolecular hydrogen bonding.

### Final Conclusion
Based on the analysis:
- Acetic acid (I) exhibits intermolecular hydrogen bonding.
- o-Nitrophenol (II) exhibits intermolecular hydrogen bonding.
- m-Nitrophenol (III) exhibits intermolecular hydrogen bonding.
- o-Boric acid (IV) exhibits intermolecular hydrogen bonding.

The correct answer is that all four molecules exhibit intermolecular hydrogen bonding.