Given are cyclohexanol `(I)`, acetic acid `(II),2,4,6-`trinitrophenol `(III)` and phenol `(IV)`. In these the order of decreasing acidic character will be:
(a)`III gt II gt IV gt I`
(b)`II gt III gt I gt IV`
(c)`II gt III gt IV gt I`
(d)`III gt IV gt II gt I`

Options

A. `III gt II gt IV gt I`
B. II gt III gt I gt IV
C. ) II gt III gt IV gt I
D. III gt IV gt II gt I

Answer

To determine the order of decreasing acidic character among cyclohexanol (I), acetic acid (II), 2,4,6-trinitrophenol (III), and phenol (IV), we need to analyze the acidity of each compound based on the stability of their conjugate bases.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Cyclohexanol (I): An aliphatic alcohol with the structure \( C_6H_{11}OH \).
- Acetic Acid (II): A carboxylic acid with the structure \( CH_3COOH \).
- 2,4,6-Trinitrophenol (III): A phenolic compound with three nitro groups attached to the benzene ring.
- Phenol (IV): A simple aromatic compound with the structure \( C_6H_5OH \).

2. **Understanding Acidity**:
- Acidity is determined by the ability of a compound to donate a proton (H⁺) and the stability of the resulting conjugate base.
- The more stable the conjugate base, the stronger the acid.

3. **Analyze Each Compound**:
- **Cyclohexanol (I)**: The conjugate base formed is cyclohexoxide, which is not stabilized by resonance. Therefore, it has the lowest acidity.
- **Acetic Acid (II)**: The conjugate base is acetate (CH₃COO⁻), which is stabilized by resonance between the two oxygen atoms. This gives it moderate acidity.
- **Phenol (IV)**: The conjugate base is phenoxide (C₆H₅O⁻), which is also stabilized by resonance with the benzene ring. It is more acidic than acetic acid.
- **2,4,6-Trinitrophenol (III)**: The conjugate base is highly stabilized by the three electron-withdrawing nitro groups, which enhance the resonance stabilization of the phenoxide ion. This makes it the most acidic among the four compounds.

4. **Order of Acidity**:
Based on the analysis:
- 2,4,6-Trinitrophenol (III) > Acetic Acid (II) > Phenol (IV) > Cyclohexanol (I)

5. **Final Answer**:
The order of decreasing acidic character is:
**(III) > (II) > (IV) > (I)**

### Conclusion:
The correct answer is option **(c) II > III > IV > I**.