What is the correct increasing order of acidic strength in the following :
(i) Phenol (ii) p-cresol (iii) p-nitrophenol (iv) o-nitrophenol ?

Explanation

To determine the correct increasing order of acidic strength among phenol, p-cresol, p-nitrophenol, and o-nitrophenol, we need to analyze the structures and the effects of substituents on the acidity of these compounds.

### Step 1: Draw the Structures
1. **Phenol**: This has a hydroxyl group (-OH) attached to a benzene ring.
2. **p-Cresol**: This is phenol with a methyl group (-CH3) attached to the para position of the benzene ring.
3. **p-Nitrophenol**: This is phenol with a nitro group (-NO2) attached to the para position of the benzene ring.
4. **o-Nitrophenol**: This is phenol with a nitro group (-NO2) attached to the ortho position of the benzene ring.

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