The decasing nucleophilic order of the following compounds is:
i. `H_(2)O`, ii. `H_(2)S`, iii. `H_(2)Se`, iv. `H_(2)Te`

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. `(iv) gt (ii) gt (i) gt (iii)`

Explanation

To determine the decreasing nucleophilic order of the compounds \(H_2O\), \(H_2S\), \(H_2Se\), and \(H_2Te\), we can follow these steps:

### Step 1: Identify the Compounds
The compounds given are:
1. \(H_2O\) (Water)
2. \(H_2S\) (Hydrogen sulfide)
3. \(H_2Se\) (Hydrogen selenide)
4. \(H_2Te\) (Hydrogen telluride)

### Step 2: Understand Nucleophilicity
Nucleophiles are species that donate an electron pair to form a chemical bond. The strength of nucleophiles can be influenced by their basicity, especially when they belong to the same group in the periodic table.

### Step 3: Basicity Order
For the compounds given, we first need to establish their basicity. Basicity generally decreases as we move down a group in the periodic table due to the increase in atomic size and the decrease in electron density. The basicity order for these compounds is:
- \(H_2O > H_2S > H_2Se > H_2Te\)

### Step 4: Reverse the Basicity Order for Nucleophilicity
Since the nucleophilic strength is the reverse of the basicity for compounds in the same group, we reverse the order we just established:
- Nucleophilic order: \(H_2Te > H_2Se > H_2S > H_2O\)

### Step 5: Conclusion
Thus, the decreasing nucleophilic order of the given compounds is:
\[ H_2Te > H_2Se > H_2S > H_2O \]

### Final Answer
The answer to the question is:
- \(H_2Te > H_2Se > H_2S > H_2O\)