The leaving group is that functional group which is ejected with `overline e^, s` of the `sigma` -bond in a reaction. Better the leaving group, faster is the reaction. The relative leaving ability of the leaving group `X` in `(R - X)` is increased by :
(i) The polarisability of `(R - X)` bond.
(ii) The stability of `X^(Ө)`.
(iii) The degree of stabilisation through solvation of `X`.
(iv) The strength of `(R - X)` bond.
The leaving group tendency is also called fugacity.
Which of the following is the wrong order of fugacity ?

Options

A. `SbH_3 gt AsH_3 gt PH_3 gt NH_3`
B. `F^(Ө) gt overset (Ө) O H gt overset (Ө) N H_2 gt overset (Ө) C H_3`
C. `NH_3 gt NH_2 - NH_2 gt MeNH-NH -Me gt Me_2 N-Nme_2`
D. `C overset (Ө) N gt overset (Ө) OH gt MeO gt overset (Ө) CH_3`.

Explanation

To determine the wrong order of fugacity based on the leaving group ability, we need to analyze the factors affecting the leaving group tendency and how they relate to basicity and acidity.

### Step-by-Step Solution:

1. **Understanding Fugacity**:
- Fugacity is a term used to describe the tendency of a leaving group to depart from a molecule. It is inversely proportional to basicity; as basicity increases, the ability of the leaving group decreases.

2. **Identifying the Leaving Groups**:
- The leaving groups mentioned in the question are:
- \( \text{SBH}_3 \)
- \( \text{ASH}_3 \)
- \( \text{PH}_3 \)
- \( \text{NH}_3 \)

3. **Basicity Order**:
- The basicity order of these amines is:
- \( \text{NH}_3 > \text{PH}_3 > \text{ASH}_3 > \text{SBH}_3 \)
- This means that \( \text{NH}_3 \) is the strongest base and \( \text{SBH}_3 \) is the weakest.

4. **Fugacity Order**:
- Since fugacity is inversely proportional to basicity, the order of fugacity will be the reverse:
- \( \text{SBH}_3 > \text{ASH}_3 > \text{PH}_3 > \text{NH}_3 \)

5. **Analyzing Other Groups**:
- For the acidic strength of the groups:
- \( \text{HF} > \text{H}_2\text{O} > \text{NH}_3 > \text{CH}_4 \)
- The order of fugacity based on acidity would be the reverse:
- \( \text{CH}_4 > \text{NH}_3 > \text{H}_2\text{O} > \text{HF} \)

6. **Degree of Amines**:
- For amines, the order of basicity is:
- \( \text{1°} > \text{2°} > \text{3°} \)
- Thus, the order of fugacity would be:
- \( \text{3°} < \text{2°} < \text{1°} \)

7. **Final Comparison**:
- The last group to analyze is:
- \( \text{CN}^- > \text{CH}_3\text{O}^- > \text{OH}^- > \text{CH}_3^- \)
- The correct order of fugacity should be:
- \( \text{CH}_3^- < \text{OH}^- < \text{CH}_3\text{O}^- < \text{CN}^- \)

8. **Identifying the Wrong Order**:
- The wrong order of fugacity is identified as:
- \( \text{OH}^- > \text{CH}_3\text{O}^- \) which contradicts the expected trend.

### Conclusion:
The wrong order of fugacity is the one where \( \text{OH}^- \) is incorrectly placed above \( \text{CH}_3\text{O}^- \).