Which of the following possess two lone pair of electrons on the central atom and square planar in shape ?
(I) `SF_(4) " " (II)XeO_(4) " " (III)XeF_(4) " " (IV)IC l_(4)^(-)`

Options

A. I,III
B. II,IV
C. III, IV
D. All

Answer

To determine which of the given molecules possess two lone pairs of electrons on the central atom and have a square planar shape, we will analyze each option step by step.

### Step 1: Analyze SF₄
1. **Valence Electrons Calculation**:
- Sulfur (S) has 6 valence electrons.
- Each Fluorine (F) has 7 valence electrons, and there are 4 Fluorine atoms.
- Total valence electrons = 6 (S) + 4 × 7 (F) = 6 + 28 = 34 electrons.

2. **Bond Pairs and Lone Pairs**:
- Divide total valence electrons by 8 to find bond pairs: 34 ÷ 8 = 4 (bond pairs).
- Remainder = 34 - 32 = 2.
- Divide the remainder by 2 to find lone pairs: 2 ÷ 2 = 1 lone pair.

3. **Shape**:
- With 4 bond pairs and 1 lone pair, the geometry is seesaw (not square planar).

### Step 2: Analyze XeO₄
1. **Valence Electrons Calculation**:
- Xenon (Xe) has 8 valence electrons.
- Each Oxygen (O) has 6 valence electrons, and there are 4 Oxygen atoms.
- Total valence electrons = 8 (Xe) + 4 × 6 (O) = 8 + 24 = 32 electrons.

2. **Bond Pairs and Lone Pairs**:
- Divide total valence electrons by 8: 32 ÷ 8 = 4 (bond pairs).
- Remainder = 32 - 32 = 0.
- Lone pairs = 0 ÷ 2 = 0.

3. **Shape**:
- With 4 bond pairs and 0 lone pairs, the geometry is tetrahedral (not square planar).

### Step 3: Analyze XeF₄
1. **Valence Electrons Calculation**:
- Xenon (Xe) has 8 valence electrons.
- Each Fluorine (F) has 7 valence electrons, and there are 4 Fluorine atoms.
- Total valence electrons = 8 (Xe) + 4 × 7 (F) = 8 + 28 = 36 electrons.

2. **Bond Pairs and Lone Pairs**:
- Divide total valence electrons by 8: 36 ÷ 8 = 4 (bond pairs).
- Remainder = 36 - 32 = 4.
- Lone pairs = 4 ÷ 2 = 2.

3. **Shape**:
- With 4 bond pairs and 2 lone pairs, the geometry is square planar.

### Step 4: Analyze ICl₄⁻
1. **Valence Electrons Calculation**:
- Iodine (I) has 7 valence electrons.
- Each Chlorine (Cl) has 7 valence electrons, and there are 4 Chlorine atoms.
- The negative charge adds 1 additional electron.
- Total valence electrons = 7 (I) + 4 × 7 (Cl) + 1 (negative charge) = 7 + 28 + 1 = 36 electrons.

2. **Bond Pairs and Lone Pairs**:
- Divide total valence electrons by 8: 36 ÷ 8 = 4 (bond pairs).
- Remainder = 36 - 32 = 4.
- Lone pairs = 4 ÷ 2 = 2.

3. **Shape**:
- With 4 bond pairs and 2 lone pairs, the geometry is square planar.

### Conclusion:
The molecules that possess two lone pairs of electrons on the central atom and are square planar in shape are:
- **XeF₄**
- **ICl₄⁻**

### Final Answer:
**(III) XeF₄ and (IV) ICl₄⁻**