Which of the following have maximum electron affinity?

Options

A. `1s^(2) 2s^(2) 2p^5`
B. `1s^(2) 2s^(2) 2p^(6)`
C. `1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^5`
D. `1s^(2) 2s^(2)p^(6)3s^(2) 3p^(6)`

Explanation

To determine which of the given options has the maximum electron affinity, we will analyze each option step by step.

### Step 1: Understand Electron Affinity
Electron affinity is defined as the amount of energy released when an electron is added to a neutral gaseous atom. Elements with high electron affinity tend to gain electrons easily.

### Step 2: Identify the Elements from the Given Electron Configurations
1. **Option 1: 1s² 2s² 2p⁵**
- This configuration corresponds to Fluorine (F), which has 9 electrons.

2. **Option 2: 1s² 2s² 2p⁶**
- This configuration corresponds to Neon (Ne), which has 10 electrons.

3. **Option 3: 1s² 2s² 2p⁶ 3s² 3p⁵**
- This configuration corresponds to Chlorine (Cl), which has 17 electrons.

4. **Option 4: 1s² 2s² 2p⁶ 3s² 3p⁶**
- This configuration corresponds to Argon (Ar), which has 18 electrons.

### Step 3: Analyze the Stability of the Elements
- Neon and Argon are noble gases and are very stable due to their full outer electron shells. They have low electron affinities because they do not tend to gain electrons.
- Fluorine has a high electronegativity but experiences electron-electron repulsion in its small 2p subshell, which affects its electron affinity.
- Chlorine, being larger than Fluorine, has less electron-electron repulsion in its 3p subshell, allowing it to have a higher electron affinity.

### Step 4: Compare Electron Affinities
- **Fluorine (F)**: High electronegativity but experiences repulsion, resulting in lower electron affinity compared to Chlorine.
- **Chlorine (Cl)**: Has a higher electron affinity than Fluorine due to its larger size and lower repulsion in the 3p subshell.
- **Neon (Ne) and Argon (Ar)**: Both have very low electron affinities because they are stable noble gases.

### Conclusion
Based on the analysis, **Chlorine (Cl)**, represented by option 3 (1s² 2s² 2p⁶ 3s² 3p⁵), has the maximum electron affinity among the given options.

### Final Answer
**Option 3: 1s² 2s² 2p⁶ 3s² 3p⁵ (Chlorine) has maximum electron affinity.**

---