Which of the following is/are correct order?

Options

A. Atomic rdius `F lt O lt F^(-) lt O^(2-)`
B. 2nd ionisation energy `C lt N lt F lt O`
C. Electron affinity: `I lt Br lt F lt Cl`
D. `Z_(ef f)` (effective nuclear change): `Al lt Al^(+) lt Al^(3+) lt Al^(2+)`

Explanation

To determine which of the given orders are correct, we will analyze each option step by step.

### Step 1: Analyze Atomic Radius Order
1. **Understanding Atomic Radius**: Atomic radius generally decreases across a period from left to right due to increasing nuclear charge, which pulls electrons closer to the nucleus.
2. **Given Order**: The order provided is increasing atomic radius.
3. **Elements to Compare**: We need to compare the atomic radii of elements like Oxygen (O) and Fluorine (F).
4. **Comparison**:
- Oxygen (O) has 8 protons and 8 electrons.
- Fluorine (F) has 9 protons and 9 electrons.
- Since Fluorine has more protons, it has a greater effective nuclear charge, leading to a smaller atomic radius than Oxygen.
- Additionally, for O²⁻ (oxide ion), it has 8 protons and 10 electrons, leading to a larger radius due to increased electron-electron repulsion.
5. **Conclusion**: The order of atomic radius is correct as stated.

### Step 2: Analyze Second Ionization Energy Order
1. **Understanding Ionization Energy**: Ionization energy is the energy required to remove an electron from an atom. It generally increases across a period.
2. **Given Order**: The order is Carbon < Nitrogen < Oxygen < Fluorine.
3. **Comparison**:
- After removing one electron from Oxygen, it attains a half-filled configuration, which is particularly stable, leading to a higher second ionization energy.
- Therefore, the order should be: O > F > N > C.
4. **Conclusion**: The order of second ionization energy is correct as stated.

### Step 3: Analyze Electron Affinity Order
1. **Understanding Electron Affinity**: Electron affinity is the energy change when an electron is added to a neutral atom. It can vary across the periodic table.
2. **Given Order**: The order is Iodine < Bromine < Chlorine < Fluorine.
3. **Comparison**:
- Chlorine has a higher electron affinity than Fluorine because of the repulsion of the added electron in Fluorine due to its small size.
- Thus, the correct order is Cl > F > Br > I.
4. **Conclusion**: The order of electron affinity is correct as stated.

### Step 4: Analyze Effective Nuclear Charge Order
1. **Understanding Effective Nuclear Charge (Z_eff)**: Z_eff is the net positive charge experienced by an electron in a multi-electron atom.
2. **Given Order**: The order is Al < Al⁺ < Al²⁺ < Al³⁺.
3. **Comparison**:
- Al has 13 protons and 13 electrons, leading to a certain effective nuclear charge.
- Al⁺ has 13 protons and 12 electrons, increasing Z_eff.
- Al²⁺ has 13 protons and 11 electrons, further increasing Z_eff.
- Al³⁺ has 13 protons and 10 electrons, resulting in the highest Z_eff due to the least number of electrons.
4. **Conclusion**: The order of effective nuclear charge is incorrect as stated; the correct order should be Al³⁺ > Al²⁺ > Al⁺ > Al.

### Final Conclusion
- **Correct Orders**:
- Atomic radius: Correct
- Second ionization energy: Correct
- Electron affinity: Correct
- Effective nuclear charge: Incorrect

### Summary of Correct Orders
1. Atomic radius: Correct
2. Second ionization energy: Correct
3. Electron affinity: Correct
4. Effective nuclear charge: Incorrect