Which of the following EA order is not correct

Options

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

Answer

To determine which of the given electron affinity (EA) orders is not correct, we need to analyze each option based on the trends of electron affinity in the periodic table.

### Step-by-Step Solution:

1. **Understanding Electron Affinity**:
- Electron affinity is the energy change when an electron is added to a neutral atom in the gaseous state. Generally, it is exothermic (releases energy).
- As we move from left to right across a period, electron affinity tends to increase due to the increasing nuclear charge, which attracts electrons more strongly.
- As we move down a group, electron affinity tends to decrease because the atomic size increases, making it harder for the nucleus to attract the added electron.

2. **Analyzing the Given Options**:
- We need to evaluate the provided orders of electron affinity for correctness.

**Option 1**: Nitrogen (N) < Oxygen (O) < Sulfur (S)
- Correct order: N < O (O has higher EA than N), and O > S (O has higher EA than S).
- This order is incorrect because it states that nitrogen has a higher electron affinity than oxygen, which is not true.

**Option 2**: Chlorine (Cl) < Oxygen (O) < Nitrogen (N) < Carbon (C)
- Correct order: Cl > O > N > C (O has higher EA than Cl, N has higher EA than C).
- This order is also incorrect because it suggests that chlorine has a lower electron affinity than oxygen.

**Option 3**: Oxygen (O) < Sulfur (S) < Chlorine (Cl)
- Correct order: O > S (O has higher EA than S) and Cl > O (Cl has higher EA than O).
- This order is incorrect because it suggests that oxygen has a lower electron affinity than sulfur.

**Option 4**: Boron (B) < Carbon (C) < Silicon (Si) < Sulfur (S)
- Correct order: B < C (C has higher EA than B), C > Si (C has higher EA than Si), and Si < S (Si has lower EA than S).
- This order is correct.

3. **Conclusion**:
- The first option (N < O < S) is not correct because nitrogen has a lower electron affinity than oxygen, and oxygen has a higher electron affinity than sulfur.
- Therefore, the answer is **Option 1**.