Which of these molecules have non-bonding electron pairs on the central atom?
`I. SF_(4)" "II. ICl_(3)" " III. SO_(2)`
The correct option is :

Options

A. II only
B. I and II only
C. I and III only
D. I, II and III

Explanation

To determine which of the given molecules have non-bonding electron pairs (lone pairs) on the central atom, we will analyze each molecule one by one.

### Step 1: Analyze SF₄

1. **Determine the central atom**: In SF₄, sulfur (S) is the central atom.
2. **Count valence electrons**: Sulfur has 6 valence electrons, and each fluorine (F) has 7 valence electrons. Since there are 4 fluorine atoms, the total number of valence electrons is:
\[ 6 + (4 \times 7) = 6 + 28 = 34 \text{ valence electrons} \]
3. **Form bonds**: Sulfur forms 4 single bonds with the 4 fluorine atoms, using 4 of its valence electrons.
4. **Calculate remaining electrons**:
\[ 34 - 4 = 30 \text{ electrons left} \]
Since each bond uses 2 electrons, and we have 4 bonds, we have 4 electrons used in bonding.
5. **Determine lone pairs**: The remaining electrons will be placed on the central atom. Sulfur will have:
\[ 6 - 4 = 2 \text{ electrons remaining} \]
These 2 electrons form 1 lone pair.
6. **Conclusion for SF₄**: SF₄ has 1 lone pair on the central atom.

### Step 2: Analyze ICl₃

1. **Determine the central atom**: In ICl₃, iodine (I) is the central atom.
2. **Count valence electrons**: Iodine has 7 valence electrons, and each chlorine (Cl) has 7 valence electrons. Since there are 3 chlorine atoms, the total number of valence electrons is:
\[ 7 + (3 \times 7) = 7 + 21 = 28 \text{ valence electrons} \]
3. **Form bonds**: Iodine forms 3 single bonds with the 3 chlorine atoms, using 3 of its valence electrons.
4. **Calculate remaining electrons**:
\[ 28 - 3 = 25 \text{ electrons left} \]
5. **Determine lone pairs**: Iodine will have:
\[ 7 - 3 = 4 \text{ electrons remaining} \]
These 4 electrons form 2 lone pairs.
6. **Conclusion for ICl₃**: ICl₃ has 2 lone pairs on the central atom.

### Step 3: Analyze SO₂

1. **Determine the central atom**: In SO₂, sulfur (S) is the central atom.
2. **Count valence electrons**: Sulfur has 6 valence electrons, and each oxygen (O) has 6 valence electrons. Since there are 2 oxygen atoms, the total number of valence electrons is:
\[ 6 + (2 \times 6) = 6 + 12 = 18 \text{ valence electrons} \]
3. **Form bonds**: Sulfur forms 2 double bonds with the 2 oxygen atoms. Each double bond uses 2 of sulfur's valence electrons.
4. **Calculate remaining electrons**:
\[ 18 - 4 = 14 \text{ electrons left} \]
5. **Determine lone pairs**: Sulfur will have:
\[ 6 - 4 = 2 \text{ electrons remaining} \]
These 2 electrons form 1 lone pair.
6. **Conclusion for SO₂**: SO₂ has 1 lone pair on the central atom.

### Final Conclusion

All three molecules (SF₄, ICl₃, and SO₂) have non-bonding electron pairs on the central atom.

### Answer:
The correct options are I, II, and III.

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