The decreasing basic order of the following 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 basic order of the given species, we will follow these steps:

### Step 1: Identify the Species
The species we need to analyze are:
1. \( \overset{o-}{C}H_3 \) (methanide ion)
2. \( \overset{o-}{O}H \) (hydroxide ion)
3. \( CH_3COO^{o-} \) (acetate ion)
4. \( H_2O \) (water)

### Step 2: Determine the Conjugate Acids
To find the basicity of these species, we will determine their conjugate acids by adding a proton (\( H^+ \)) to each species:
1. For \( \overset{o-}{C}H_3 \): Adding \( H^+ \) gives \( CH_4 \) (methane).
2. For \( \overset{o-}{O}H \): Adding \( H^+ \) gives \( H_2O \) (water).
3. For \( CH_3COO^{o-} \): Adding \( H^+ \) gives \( CH_3COOH \) (acetic acid).
4. For \( H_2O \): Adding \( H^+ \) gives \( H_3O^+ \) (hydronium ion).

### Step 3: Rank the Conjugate Acids
Now we will rank the acidic strength of the conjugate acids:
1. \( H_3O^+ \) (hydronium ion) - most acidic
2. \( CH_3COOH \) (acetic acid) - second most acidic
3. \( H_2O \) (water) - less acidic
4. \( CH_4 \) (methane) - least acidic

### Step 4: Determine the Basic Strength Order
The basic strength order is the opposite of the acidic strength order:
1. \( \overset{o-}{C}H_3 \) (methanide ion) - strongest base
2. \( \overset{o-}{O}H \) (hydroxide ion) - second strongest base
3. \( CH_3COO^{o-} \) (acetate ion) - weaker base
4. \( H_2O \) (water) - weakest base

### Step 5: Write the Final Basic Order
Thus, the decreasing basic order of the given species is:
1. \( \overset{o-}{C}H_3 \) (methanide ion)
2. \( \overset{o-}{O}H \) (hydroxide ion)
3. \( CH_3COO^{o-} \) (acetate ion)
4. \( H_2O \) (water)

### Final Answer
The decreasing basic order is:
**\( \overset{o-}{C}H_3 > \overset{o-}{O}H > CH_3COO^{o-} > H_2O \)**

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