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
- **Concept**: Anions are larger than cations due to the greater number of electrons, which leads to electron-electron repulsion. Conversely, cations are smaller because they lose electrons.
- **Order Given**: F⁻ > Na⁺ > Mg²⁺ > Al³⁺
- **Analysis**:
- F⁻ (an anion) has the largest size.
- Na⁺ (a cation) is smaller than F⁻.
- Mg²⁺ is smaller than Na⁺ due to a higher positive charge.
- Al³⁺ is the smallest due to the highest positive charge.
- **Conclusion**: The order is correct.

### Step 2: Analyze Increasing Ionization Energy
- **Concept**: Ionization energy increases across a period due to decreasing atomic size. However, nitrogen has a half-filled p subshell, which gives it a higher ionization energy than oxygen.
- **Order Given**: B < C < N < O
- **Analysis**:
- B (boron) has the lowest ionization energy.
- C (carbon) is higher than B.
- N (nitrogen) should have a higher ionization energy than O due to its half-filled configuration.
- O (oxygen) should have a lower ionization energy than N.
- **Conclusion**: This order is incorrect because N > O in terms of ionization energy.

### Step 3: Analyze Electron Affinity
- **Concept**: Electron affinity generally decreases down a group due to increasing atomic size. However, chlorine has a higher electron affinity than fluorine due to repulsions in the small 2p subshell of fluorine.
- **Order Given**: F > Cl > Br > I
- **Analysis**:
- F has a lower electron affinity than Cl due to repulsions.
- Cl has a higher electron affinity than Br and I as we move down the group.
- **Conclusion**: The order is correct.

### Step 4: Analyze Increasing Metallic Radius
- **Concept**: The metallic radius increases down a group due to an increase in the number of electron shells.
- **Order Given**: Li < Na < K < Rb
- **Analysis**:
- As we move down the group from Li to Rb, the size indeed increases.
- **Conclusion**: The order is correct.

### Final Conclusion
The arrangement that is not correct according to the property indicated is the one regarding increasing ionization energy (Step 2). Thus, the answer is:

**Incorrect Order**: B < C < N < O (N should be greater than O)

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