Which is chemically most active non-metal ?

Options

A. S
B. O
C. F
D. N

Explanation

To determine which is the chemically most active non-metal among the given options, we will analyze the electronic configurations and reactivity of each non-metal listed.

### Step-by-Step Solution:

1. **Identify the Non-Metals and Their Atomic Numbers**:
- Sulphur (S): Atomic number 16
- Oxygen (O): Atomic number 8
- Fluorine (F): Atomic number 9
- Nitrogen (N): Atomic number 7

2. **Determine the Electronic Configurations**:
- Sulphur: 1s² 2s² 2p⁶ 3s² 3p⁴ (Valence: ns² np⁴)
- Oxygen: 1s² 2s² 2p⁴ (Valence: ns² np⁴)
- Fluorine: 1s² 2s² 2p⁵ (Valence: ns² np⁵)
- Nitrogen: 1s² 2s² 2p³ (Valence: ns² np³)

3. **Determine the Number of Electrons Needed to Complete the Octet**:
- Sulphur needs 2 electrons to complete its octet.
- Oxygen needs 2 electrons to complete its octet.
- Fluorine needs 1 electron to complete its octet.
- Nitrogen needs 3 electrons to complete its octet.

4. **Analyze Reactivity**:
- The reactivity of non-metals generally increases with their electronegativity and the number of electrons they need to gain to complete their octet.
- Fluorine, needing only 1 electron to complete its octet, is highly reactive.
- It is also the most electronegative element, which means it has a strong tendency to attract electrons.

5. **Consider Examples of Reactivity**:
- Fluorine reacts vigorously with water to form hydrogen fluoride (HF).
- It can also react with noble gases like xenon, forming compounds such as XeF₄.

6. **Conclusion**:
- Based on the analysis of electronic configurations, the number of electrons needed to complete the octet, and its high reactivity, Fluorine (F) is identified as the most chemically active non-metal.

### Final Answer:
**Fluorine (F) is the chemically most active non-metal.**

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