Which of the following is incorrect order of property as indicated ?

Options

A. `Na^(+) lt F^(-) lt O^(2-) lt Ne lt Ar` : Atomic size
B. `Br lt Se lt As lt Ge` :Metallic character
C. `Na lt Al lt Si lt Mg` :Ionisation energy
D. `I lt Br lt Cl lt F` :Electron affinity

Explanation

To determine the incorrect order of properties among the given options, we will analyze each property step by step.

### Step 1: Analyze Atomic Size Order
- **Elements Involved**: Sodium (Na), Fluoride ion (F⁻), Oxygen (O), Helium (He).
- **Trends**: In a period, atomic size decreases from left to right due to increasing nuclear charge. Noble gases have the largest atomic size in their respective periods.
- **Expected Order**: He > F⁻ > O > Na (correct order).
- **Conclusion**: This order is correct.

### Step 2: Analyze Metallic Character Order
- **Elements Involved**: Selenium (Se), Arsenic (As), Bromine (Br).
- **Trends**: Metallic character increases down a group and decreases across a period from left to right.
- **Expected Order**: Se > As > Br (incorrect order).
- **Conclusion**: This order is incorrect because Br is more non-metallic than As and Se.

### Step 3: Analyze Ionization Energy Order
- **Elements Involved**: Silicon (Si), Magnesium (Mg), Aluminum (Al), Sodium (Na).
- **Trends**: Ionization energy increases across a period due to decreasing atomic size and increasing nuclear charge.
- **Expected Order**: Si > Mg > Al > Na (correct order).
- **Conclusion**: This order is correct.

### Step 4: Analyze Electron Affinity Order
- **Elements Involved**: Iodine (I), Bromine (Br), Chlorine (Cl), Fluorine (F).
- **Trends**: Electron affinity generally increases across a period, but fluorine has lower electron affinity than chlorine due to inter-electronic repulsion.
- **Expected Order**: Cl > F > Br > I (correct order).
- **Conclusion**: This order is correct.

### Final Conclusion
The incorrect order is found in the metallic character property. Therefore, the answer to the question is that the incorrect order is in the metallic character, specifically the order given for Se, As, and Br.

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