In which of the following compounds does intramolecular `H`-bonding occure?
a. `o`-Nitro phenol
b, `o`-Cresol
c. `o`-Hydrox benzoic acid

Explanation

To determine which of the given compounds exhibit intramolecular hydrogen bonding, we will analyze each compound step by step.

### Step 1: Understanding Intramolecular Hydrogen Bonding
Intramolecular hydrogen bonding occurs when a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) forms a bond with another electronegative atom within the same molecule. This typically involves a hydrogen atom attached to an -OH or -NH group and another electronegative atom in close proximity.

### Step 2: Analyzing Ortho-Nitrophenol
- **Structure**: Ortho-nitrophenol has a hydroxyl group (-OH) and a nitro group (-NO2) at the ortho position on the benzene ring.
- **Hydrogen Bonding**: The hydrogen atom from the -OH group can form a hydrogen bond with the electronegative oxygen atom of the nitro group.
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