The decresing nuclephilic order of the following is:
i. `F_(3)CSO_(3)^(o-)`, ii. `Cl_(3)C-COO^(o-)`
iii. `PhSO_(3)^(o-)`, iv. `MeSO_(3)^(o-)`

Options

A. `(i) gt (ii) gt (iii) gt (iv)`
B. `(iv) gt (iii) gt (ii) gt (i)`
C. `(ii) gt (iv) gt (iii) gt (i)`
D. `(iv) gt (ii) gt (i) gt (iii)`

Explanation

To determine the decreasing nucleophilic order of the given species, we can analyze their basicity, as the nucleophilic strength is directly related to the stability of their conjugate acids. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Nucleophilic Centers
All four species have a negatively charged oxygen atom, which is the nucleophilic center. The species are:
1. `F_(3)CSO_(3)^(o-)`
2. `Cl_(3)C-COO^(o-)`
3. `PhSO_(3)^(o-)`
4. `MeSO_(3)^(o-)`

### Step 2: Write the Conjugate Acids
To compare their basicity, we need to find the conjugate acids of each species by adding a proton (H⁺):
1. Conjugate acid of `F_(3)CSO_(3)^(o-)` is `CF3SO3H`
2. Conjugate acid of `Cl_(3)C-COO^(o-)` is `Cl3C-COOH`
3. Conjugate acid of `PhSO_(3)^(o-)` is `PhSO3H`
4. Conjugate acid of `MeSO_(3)^(o-)` is `MeSO3H`

### Step 3: Determine the Acidity of the Conjugate Acids
Using the rules of acidity:
- Sulfonic acids are more acidic than carboxylic acids.
- Electron-withdrawing groups increase acidity, while electron-donating groups decrease acidity.

From the above:
- `CF3SO3H` is the strongest acid due to the strong electron-withdrawing effect of the trifluoromethyl group (CF3).
- `PhSO3H` is next, as the phenyl group has a moderate electron-withdrawing effect.
- `MeSO3H` is less acidic due to the electron-donating effect of the methyl group.
- `Cl3C-COOH` is the weakest acid since it is a carboxylic acid and has no strong electron-withdrawing groups compared to the sulfonic acids.

### Step 4: Establish the Basicity Order
The basicity order is the opposite of the acidity order:
1. `Cl_(3)C-COO^(o-)` (strongest base, weakest acid)
2. `MeSO_(3)^(o-)`
3. `PhSO_(3)^(o-)`
4. `F_(3)CSO_(3)^(o-)` (weakest base, strongest acid)

### Step 5: Conclude the Nucleophilic Order
Since the nucleophilic strength follows the same order as basicity when the nucleophilic center is the same, we can conclude:
- The decreasing nucleophilic order is:
1. `Cl_(3)C-COO^(o-)`
2. `MeSO_(3)^(o-)`
3. `PhSO_(3)^(o-)`
4. `F_(3)CSO_(3)^(o-)`

### Final Answer
The decreasing nucleophilic order is:
`Cl_(3)C-COO^(o-) > MeSO_(3)^(o-) > PhSO_(3)^(o-) > F_(3)CSO_(3)^(o-)`