The decreasing nucelophilic order of the following compounds is:
i. `overset(o-)(C)H_(3)`, ii.` overset(o-)(O)H`, iii. `CH_(3)COO^(o-)`, iv. `H_(2)O`

Options

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

Explanation

To determine the decreasing nucleophilic order of the given compounds, we need to analyze the nucleophilic centers and their basic strengths. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Nucleophilic Centers
The compounds provided are:
1. `overset(o-)(C)H_(3)` (methanide ion, CH3^-)
2. `overset(o-)(O)H` (hydroxide ion, OH^-)
3. `CH_(3)COO^(o-)` (acetate ion, CH3COO^-)
4. `H_(2)O` (water)

The nucleophilic centers in these compounds are:
- For `CH3^-`, the nucleophilic center is carbon (C).
- For `OH^-`, the nucleophilic center is oxygen (O).
- For `CH3COO^-`, the nucleophilic center is also oxygen (O).
- For `H2O`, the nucleophilic center is again oxygen (O).

### Step 2: Determine Basic Strengths
Since the nucleophilic centers belong to the same period (second period), we can relate nucleophilic strength to basic strength. The basic strength can be determined by analyzing the conjugate acids formed when each nucleophile accepts a proton (H+).

1. For `CH3^-`:
- Conjugate acid: CH4 (methane)
2. For `OH^-`:
- Conjugate acid: H2O
3. For `CH3COO^-`:
- Conjugate acid: CH3COOH (acetic acid)
4. For `H2O`:
- Conjugate acid: H3O+ (hydronium ion)

### Step 3: Compare the Acidity of Conjugate Acids
The strength of the conjugate acids can be compared:
- H3O+ (strongest acid)
- CH3COOH (weaker acid)
- H2O (neutral)
- CH4 (weakest acid)

### Step 4: Determine the Basic Strength Order
The basic strength order is the inverse of the acidity order:
- CH3^- (most basic)
- OH^- (next)
- CH3COO^- (less basic)
- H2O (least basic)

### Step 5: Establish the Nucleophilic Strength Order
Since the nucleophilic strength order is the same as the basic strength order for species in the same period, we can conclude:
1. CH3^- (strongest nucleophile)
2. OH^-
3. CH3COO^-
4. H2O (weakest nucleophile)

### Final Answer
The decreasing nucleophilic order of the compounds is:
**CH3^- > OH^- > CH3COO^- > H2O**