In which of the following arrangements, the order is not correct according to the property indicated against it?

Options

A. Increasing size: `Al^(3+) lt Mg^(2+) lt Na^(+) lt F^(-)`
B. Increasing I.`E_(1)`: `B lt C lt N lt O`
C. Increasing `E.A_(1):I lt Br lt F lt Cl`
D. Increasing metallic radius : `Li lt Na lt K lt Rb`

Answer

To determine which arrangement is not correct according to the indicated property, we will analyze each option step by step.

### Step 1: Analyze Increasing Size
- **Elements**: Aluminum (Al), Magnesium (Mg), Potassium (K), Fluorine ion (F⁻)
- **Analysis**:
- All these elements have the same number of electrons (10) when considering their ionic forms.
- The effective nuclear charge increases with the number of protons:
- Al (13 protons) < Mg (12 protons) < K (19 protons) < F⁻ (9 protons).
- Thus, the order of increasing size is correct as the effective nuclear charge increases, leading to a smaller size.

### Step 2: Analyze First Ionization Energy
- **Elements**: Boron (B), Carbon (C), Nitrogen (N), Oxygen (O)
- **Analysis**:
- The electronic configurations are:
- B: 1s² 2s² 2p¹
- C: 1s² 2s² 2p²
- N: 1s² 2s² 2p³ (half-filled, more stable)
- O: 1s² 2s² 2p⁴
- Nitrogen has a half-filled p subshell, which makes it more stable and requires more energy to remove an electron compared to oxygen.
- Therefore, the correct order of increasing first ionization energy should be: B < C < O < N.
- This means the given order is incorrect.

### Step 3: Analyze First Electron Affinity
- **Elements**: Iodine (I), Bromine (Br), Fluorine (F), Chlorine (Cl)
- **Analysis**:
- Generally, electron affinity increases across a period and decreases down a group.
- However, fluorine has a lower electron affinity than chlorine due to inter-electronic repulsion in its small size.
- The correct order of increasing electron affinity should be: I < Br < Cl < F.
- Thus, the given order is correct.

### Step 4: Analyze Increasing Metallic Radius
- **Elements**: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb)
- **Analysis**:
- As we move down the group, the metallic radius increases due to the addition of electron shells.
- The correct order of increasing metallic radius is: Li < Na < K < Rb.
- Therefore, this order is also correct.

### Conclusion
- The only incorrect arrangement is for the first ionization energy: **Boron < Carbon < Nitrogen < Oxygen** is the correct order, but the question suggests it is in the wrong order. Thus, the answer is **B**.