Which of the following compound obey octet rule :

Options

A. `CO_(2)`
B. `SF_(6)`
C. `PCl_(5)`
D. `SO_(3)`

Explanation

To determine which of the following compounds obey the octet rule, we need to analyze the electron configurations and bonding of each compound. The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons, achieving a stable electron configuration similar to that of noble gases.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze are CO2, SF6, PCl5, and SO3.

2. **Analyze CO2 (Carbon Dioxide)**:
- **Valence Electrons**: Carbon (C) has 4 valence electrons, and each Oxygen (O) has 6 valence electrons.
- **Total Electrons**: 4 (C) + 2 × 6 (O) = 16 valence electrons.
- **Bonding**: Carbon forms double bonds with each oxygen atom (C=O).
- **Octet Completion**: Carbon shares 4 electrons (2 from each O), achieving a total of 8 electrons (4 from its own and 4 shared).
- **Conclusion**: CO2 obeys the octet rule.

3. **Analyze SF6 (Sulfur Hexafluoride)**:
- **Valence Electrons**: Sulfur (S) has 6 valence electrons, and each Fluorine (F) has 7 valence electrons.
- **Total Electrons**: 6 (S) + 6 × 7 (F) = 48 valence electrons.
- **Bonding**: Sulfur forms single bonds with each of the six fluorine atoms.
- **Octet Completion**: Sulfur has 12 electrons around it (6 from the bonds), exceeding the octet.
- **Conclusion**: SF6 does not obey the octet rule.

4. **Analyze PCl5 (Phosphorus Pentachloride)**:
- **Valence Electrons**: Phosphorus (P) has 5 valence electrons, and each Chlorine (Cl) has 7 valence electrons.
- **Total Electrons**: 5 (P) + 5 × 7 (Cl) = 40 valence electrons.
- **Bonding**: Phosphorus forms single bonds with five chlorine atoms.
- **Octet Completion**: Phosphorus has 10 electrons around it (5 from the bonds), exceeding the octet.
- **Conclusion**: PCl5 does not obey the octet rule.

5. **Analyze SO3 (Sulfur Trioxide)**:
- **Valence Electrons**: Sulfur (S) has 6 valence electrons, and each Oxygen (O) has 6 valence electrons.
- **Total Electrons**: 6 (S) + 3 × 6 (O) = 24 valence electrons.
- **Bonding**: Sulfur forms double bonds with three oxygen atoms.
- **Octet Completion**: Sulfur shares 6 electrons (2 from each O), achieving a total of 12 electrons around sulfur.
- **Conclusion**: SO3 does not obey the octet rule.

### Final Conclusion:
The only compound that obeys the octet rule is **CO2**.