Arrange the order of `C-OH` bond length of the following compounds. (A) Methanol (B) Phenol (C) p-Ethoxyphenol

Options

A. `A gt B gt C`
B. `A gt C gt B`
C. `C gt B gt A`
D. `B gt C gt A`

Explanation

To determine the order of C-OH bond lengths in the compounds methanol (A), phenol (B), and p-ethoxyphenol (C), we need to analyze the structure and bonding characteristics of each compound.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- **Methanol (A)**: CH₃OH
- **Phenol (B)**: C₆H₅OH
- **p-Ethoxyphenol (C)**: C₆H₄(OC₂H₅)OH (where the ethoxy group is at the para position relative to the hydroxyl group)

2. **Analyze the Bonding**:
- In **methanol**, the C-O bond is a single bond (C-OH), and it is sp³ hybridized. This bond generally has a longer bond length due to the absence of any resonance or double bond character.
- In **phenol**, the C-O bond is also a single bond, but the oxygen has a lone pair that can participate in resonance with the aromatic ring. This resonance leads to a partial double bond character in the C-O bond, making it shorter than the C-O bond in methanol.
- In **p-ethoxyphenol**, the presence of the ethoxy group (which has a +M effect) can also participate in resonance. However, this resonance can decrease the double bond character of the C-O bond compared to phenol, leading to a longer C-O bond than in phenol but shorter than in methanol.

3. **Order of C-O Bond Lengths**:
- Methanol (A) has the longest C-O bond length due to being a simple alcohol with no resonance.
- p-Ethoxyphenol (C) has a longer C-O bond length than phenol (B) due to the +M effect of the ethoxy group reducing the double bond character.
- Phenol (B) has the shortest C-O bond length due to resonance providing partial double bond character.

4. **Final Arrangement**:
- The order of C-OH bond lengths from longest to shortest is:
- **A (Methanol) > C (p-Ethoxyphenol) > B (Phenol)**

### Conclusion:
The final order of C-OH bond lengths is:
**A > C > B**