Which of the following is/are correct order/s of electron affinity.

Options

A. `N lt C lt O lt F`
B. `P lt Si lt S lt Cl`
C. `Si lt P lt S < Cl`
D. `C lt N lt O lt F`

Answer

To determine the correct order of electron affinity among the given options, we need to understand the concept of electron affinity and the periodic trends associated with it.

### Step-by-Step Solution:

1. **Understand Electron Affinity**:
- Electron affinity is the amount of energy released when an electron is added to a neutral atom in the gas phase. It is often expressed in terms of electron gain enthalpy (ΔE).
- Generally, as we move across a period from left to right, the electron affinity becomes more negative (i.e., increases) because the effective nuclear charge increases, making it easier for the atom to attract an additional electron.

2. **Identify Anomalies**:
- There is an anomaly between Group 14 (carbon group) and Group 15 (nitrogen group) elements. Group 15 elements have a half-filled p-orbital configuration (Ns²Np³), which is more stable and thus less likely to gain an additional electron compared to Group 14 elements (Ns²Np²).

3. **Compare Electron Affinities**:
- For elements in Group 14 and Group 15:
- Carbon (Group 14) has a higher electron affinity than Nitrogen (Group 15).
- This means that the order for these elements is:
- Nitrogen < Carbon

4. **Consider Other Groups**:
- Moving to Group 16 (Oxygen) and Group 17 (Fluorine):
- Oxygen has a higher electron affinity than Nitrogen.
- Fluorine has a higher electron affinity than Oxygen.
- Therefore, the order is:
- Nitrogen < Carbon < Oxygen < Fluorine

5. **Evaluate Given Options**:
- Check the provided options for their correctness based on the established order:
- **Option A**: Nitrogen < Carbon < Oxygen < Fluorine (Correct)
- **Option B**: Phosphorus (Group 15) < Silicon (Group 14) (Correct, as Group 14 > Group 15)
- **Option C**: Carbon < Nitrogen (Incorrect, as Carbon has a higher electron affinity than Nitrogen)
- **Option D**: (Not provided in the transcript, but can be evaluated similarly)

6. **Conclusion**:
- The correct orders of electron affinity are A and B.

### Final Answer:
The correct orders of electron affinity are A and B.