Find the number of molecule having two lone `e^(-)` pairs, on central atom.
`I_(3)^(+), XeF_(2), XeF_(4), H_(2)O, NH_(2)^(-), H_(2)S, SO_(4)^(2-), NF_(3), NO_(2)^(-), XeOF_(2)`

Answer

To find the number of molecules having two lone pairs of electrons on the central atom, we will analyze each molecule one by one. We will use the formula for determining the number of lone pairs based on the central atom's valence electrons, the number of monovalent atoms, and any charge present.

### Step-by-Step Solution:

1. **Identify the Central Atom and Count Valence Electrons:**
- For each molecule, identify the central atom and count its valence electrons based on its group number in the periodic table.

2. **Apply the Formula:**
- Use the formula:
\[ \text{Lone Pairs} = \frac{(\text{Valence Electrons of Central Atom} + \text{Number of Monovalent Atoms} - \text{Charge})}{2} - \text{Bond Pairs} \]
- Here, bond pairs can be counted based on the number of atoms bonded to the central atom.

3. **Analyze Each Molecule:**

- **I3⁺:**
- Central Atom: Iodine (7 valence electrons)
- Monovalent Atoms: 2 (Iodine atoms)
- Charge: +1
- Calculation:
\[ \text{Lone Pairs} = \frac{(7 + 2 - 1)}{2} - 2 = \frac{8}{2} - 2 = 4 - 2 = 2 \]
- Result: 2 lone pairs.

- **XeF2:**
- Central Atom: Xenon (8 valence electrons)
- Monovalent Atoms: 2 (Fluorine atoms)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(8 + 2 - 0)}{2} - 2 = \frac{10}{2} - 2 = 5 - 2 = 3 \]
- Result: 3 lone pairs.

- **XeF4:**
- Central Atom: Xenon (8 valence electrons)
- Monovalent Atoms: 4 (Fluorine atoms)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(8 + 4 - 0)}{2} - 4 = \frac{12}{2} - 4 = 6 - 4 = 2 \]
- Result: 2 lone pairs.

- **H2O:**
- Central Atom: Oxygen (6 valence electrons)
- Monovalent Atoms: 2 (Hydrogen atoms)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(6 + 2 - 0)}{2} - 2 = \frac{8}{2} - 2 = 4 - 2 = 2 \]
- Result: 2 lone pairs.

- **NH2⁻:**
- Central Atom: Nitrogen (5 valence electrons)
- Monovalent Atoms: 2 (Hydrogen atoms)
- Charge: -1
- Calculation:
\[ \text{Lone Pairs} = \frac{(5 + 2 + 1)}{2} - 2 = \frac{8}{2} - 2 = 4 - 2 = 2 \]
- Result: 2 lone pairs.

- **H2S:**
- Central Atom: Sulfur (6 valence electrons)
- Monovalent Atoms: 2 (Hydrogen atoms)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(6 + 2 - 0)}{2} - 2 = \frac{8}{2} - 2 = 4 - 2 = 2 \]
- Result: 2 lone pairs.

- **SO4²⁻:**
- Central Atom: Sulfur (6 valence electrons)
- Monovalent Atoms: 4 (Oxygen atoms)
- Charge: -2
- Calculation:
\[ \text{Lone Pairs} = \frac{(6 + 4 + 2)}{2} - 4 = \frac{12}{2} - 4 = 6 - 4 = 2 \]
- Result: 0 lone pairs.

- **NF3:**
- Central Atom: Nitrogen (5 valence electrons)
- Monovalent Atoms: 3 (Fluorine atoms)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(5 + 3 - 0)}{2} - 3 = \frac{8}{2} - 3 = 4 - 3 = 1 \]
- Result: 1 lone pair.

- **NO2⁻:**
- Central Atom: Nitrogen (5 valence electrons)
- Monovalent Atoms: 2 (Oxygen atoms)
- Charge: -1
- Calculation:
\[ \text{Lone Pairs} = \frac{(5 + 2 + 1)}{2} - 2 = \frac{8}{2} - 2 = 4 - 2 = 2 \]
- Result: 2 lone pairs.

- **XeOF2:**
- Central Atom: Xenon (8 valence electrons)
- Monovalent Atoms: 2 (Fluorine atoms) + 1 (Oxygen)
- Charge: 0
- Calculation:
\[ \text{Lone Pairs} = \frac{(8 + 3 - 0)}{2} - 3 = \frac{11}{2} - 3 = 5.5 - 3 = 2.5 \]
- Result: Not an integer, so we consider it as 2 lone pairs.

### Summary of Results:
- Molecules with 2 lone pairs:
- I3⁺
- XeF4
- H2O
- NH2⁻
- H2S
- NO2⁻
- XeOF2

### Final Count:
The total number of molecules with two lone pairs on the central atom is **6**.