The increasing order of electron affinity of the electronic configurations of element is :-
(I) `1s^(2) 2s^(2)2p^(6)3s^(2)3p^(5)`
(II) `1s^(2) 2s^(2)2p^(3)`
(III) `1s^(2)2s^(2)2p^(5)`
(IV) `1s^(2)2s^(2)2p^(6) 3s^(1)`

Options

A. `II lt IV lt III lt I`
B. `I lt II lt IV lt III`
C. `I lt III lt II lt IV`
D. `IV lt III lt II lt I`

Explanation

To determine the increasing order of electron affinity for the given electronic configurations, we need to analyze the outer shell configurations of each element. Electron affinity is influenced by how close the outer electrons are to the nucleus and how many electrons are needed to achieve a stable noble gas configuration.

### Step-by-Step Solution:

1. **Identify the Outer Shell Configurations:**
- (I) `1s² 2s² 2p⁶ 3s² 3p⁵` → Outer shell: `3s² 3p⁵`
- (II) `1s² 2s² 2p³` → Outer shell: `2s² 2p³`
- (III) `1s² 2s² 2p⁵` → Outer shell: `2s² 2p⁵`
- (IV) `1s² 2s² 2p⁶ 3s¹` → Outer shell: `3s¹`

2. **Analyze Each Configuration:**
- **Configuration (I)**: `3s² 3p⁵` is one electron short of a full octet (noble gas configuration). Therefore, it has a relatively high electron affinity.
- **Configuration (II)**: `2s² 2p³` has a half-filled p orbital, which is relatively stable. Thus, it has a lower electron affinity compared to configurations that are closer to achieving a noble gas configuration.
- **Configuration (III)**: `2s² 2p⁵` is one electron short of a noble gas configuration (neon). It has a high electron affinity because it readily accepts one electron.
- **Configuration (IV)**: `3s¹` is also one electron short of a noble gas configuration (argon), but it is in a higher energy level (3rd shell) compared to the 2nd shell configurations.

3. **Rank the Configurations Based on Electron Affinity:**
- **Highest Electron Affinity**: Configuration (III) `2s² 2p⁵` (needs 1 electron to achieve noble gas configuration)
- **Next Highest**: Configuration (I) `3s² 3p⁵` (needs 1 electron, but in a higher energy level)
- **Next**: Configuration (IV) `3s¹` (needs 1 electron but is less stable than the previous two)
- **Lowest Electron Affinity**: Configuration (II) `2s² 2p³` (stable half-filled configuration)

4. **Final Order**:
- (III) > (I) > (IV) > (II)

### Increasing Order of Electron Affinity:
- (II) < (IV) < (I) < (III)