Which is the correct property mentioned `-`

Options

A. `Fe^(+) lt Fe^(2+) lt Fe^(3+)-`size
B. `Fe^(+) lt Fe^(2+) lt Fe^(3+)-`ionisation energy
C. `B lt Be lt C-`ionisation energy
D. `N lt O lt F-`ionisation energy

Explanation

To solve the question regarding the correct property mentioned, we will analyze the properties of iron ions (Fe²⁺ and Fe³⁺), the ionization energies of boron, beryllium, and carbon, and the ionization energies of nitrogen, oxygen, and fluorine step by step.

### Step 1: Analyze the Size of Iron Ions (Fe²⁺ and Fe³⁺)
- **Concept**: The size of an ion is influenced by the number of electrons and the nuclear charge.
- **Fe²⁺**: Iron loses 2 electrons. The remaining electrons are attracted by the same number of protons (26 protons).
- **Fe³⁺**: Iron loses 3 electrons. Again, the remaining electrons are attracted by the same number of protons.
- **Conclusion**: Since Fe³⁺ has one less electron than Fe²⁺, it will be smaller in size because the same nuclear charge attracts fewer electrons more strongly.

### Step 2: Analyze Ionization Energy of Iron Ions
- **Concept**: Ionization energy is the energy required to remove an electron from an atom or ion. Smaller ions have higher ionization energies due to stronger attraction between the nucleus and the electrons.
- **Comparison**:
- Fe³⁺ has a smaller size than Fe²⁺, thus it has a higher ionization energy.
- Fe²⁺ has a higher ionization energy than Fe⁺.
- **Conclusion**: The order of ionization energy is Fe³⁺ > Fe²⁺ > Fe⁺.

### Step 3: Analyze Ionization Energies of Boron, Beryllium, and Carbon
- **Electronic Configurations**:
- Boron (B): 1s² 2s² 2p¹
- Beryllium (Be): 1s² 2s²
- Carbon (C): 1s² 2s² 2p²
- **Concept**: As we move from left to right in the periodic table, the size decreases and ionization energy increases.
- **Stability**: Beryllium has a fully filled 2s orbital, which is more stable than boron's configuration.
- **Conclusion**: The order of ionization energy is Be > B > C.

### Step 4: Analyze Ionization Energies of Nitrogen, Oxygen, and Fluorine
- **Electronic Configurations**:
- Nitrogen (N): 1s² 2s² 2p³
- Oxygen (O): 1s² 2s² 2p⁴
- Fluorine (F): 1s² 2s² 2p⁵
- **Concept**: As we move from left to right, the size decreases and ionization energy increases. However, nitrogen has a half-filled stable configuration, making it more stable than oxygen.
- **Conclusion**: The order of ionization energy is N > O > F.

### Final Conclusion
After analyzing the properties mentioned:
1. The size of Fe²⁺ and Fe³⁺ is correctly mentioned.
2. The ionization energy of Fe³⁺ is greater than Fe²⁺ and Fe⁺, which is correctly mentioned.
3. The ionization energy of beryllium is greater than boron, which is correctly mentioned.
4. The ionization energy of nitrogen is greater than oxygen, which is correctly mentioned.

Thus, the correct property mentioned is related to the ionization energies of the elements analyzed.