Octet rule is not satisfied for which of the following molecules?

Options

A. `Cl_2`
B. `CO_2`
C. `N_2`
D. `NO`

Answer

To determine which molecule does not satisfy the octet rule, we need to analyze the valence electrons of the elements involved in each molecule and how they share or bond with each other. The octet rule states that atoms tend to form bonds until they are surrounded by eight valence electrons.

### Step-by-Step Solution:

1. **Understanding the Octet Rule**:
The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer shell of eight electrons.

2. **Analyzing Cl2 (Chlorine)**:
- Chlorine (Cl) is in Group 17 and has 7 valence electrons.
- In Cl2, each Cl atom shares one electron with the other, resulting in each Cl atom having 8 electrons (7 from its own + 1 shared).
- **Conclusion**: Cl2 satisfies the octet rule.

3. **Analyzing CO2 (Carbon Dioxide)**:
- Carbon (C) is in Group 14 and has 4 valence electrons.
- Oxygen (O) is in Group 16 and has 6 valence electrons.
- In CO2, carbon forms double bonds with each oxygen atom, allowing both carbon and oxygen to achieve an octet.
- **Conclusion**: CO2 satisfies the octet rule.

4. **Analyzing N2 (Nitrogen)**:
- Nitrogen (N) is in Group 15 and has 5 valence electrons.
- In N2, two nitrogen atoms form a triple bond, which allows each nitrogen atom to have 8 electrons.
- **Conclusion**: N2 satisfies the octet rule.

5. **Analyzing NO (Nitric Oxide)**:
- Nitrogen (N) has 5 valence electrons, and oxygen (O) has 6 valence electrons.
- In NO, nitrogen and oxygen form a bond, but nitrogen ends up with only 7 electrons (5 from its own + 2 shared with oxygen), while oxygen has 8 electrons.
- **Conclusion**: NO does not satisfy the octet rule because nitrogen has only 7 electrons.

### Final Answer:
The molecule that does not satisfy the octet rule is **NO (Nitric Oxide)**.