Which of the following is the correct order of ionisation enthalpy ?
(1)Be+ > Be
(2) O > N
(3) C > Be
(4) F > Ne

Options

A. 2,3
B. 3,4
C. 1,3
D. 1,2

Explanation

To determine the correct order of ionization enthalpy among the given options, we need to analyze each statement based on the principles of atomic structure and periodic trends.

### Step-by-Step Solution:

1. **Understanding Ionization Enthalpy**:
- Ionization enthalpy (or ionization energy) is the energy required to remove the outermost electron from an atom or ion. Generally, ionization energy increases across a period and decreases down a group in the periodic table.

2. **Analyzing Statement (1): Be+ > Be**:
- Beryllium (Be) has an atomic number of 4 with the electronic configuration of 1s² 2s².
- Beryllium ion (Be⁺) has lost one electron, resulting in an electronic configuration of 1s² 2s¹.
- Because Be⁺ has a higher effective nuclear charge acting on fewer electrons, it will require more energy to remove the remaining electron compared to neutral Be.
- **Conclusion**: This statement is **correct**.

3. **Analyzing Statement (2): O > N**:
- Oxygen (O) has an atomic number of 8 (1s² 2s² 2p⁴) and nitrogen (N) has an atomic number of 7 (1s² 2s² 2p³).
- Nitrogen has a half-filled p subshell (2p³), which is more stable than oxygen's 2p⁴ configuration. Thus, it is harder to remove an electron from nitrogen than from oxygen.
- **Conclusion**: This statement is **incorrect**.

4. **Analyzing Statement (3): C > Be**:
- Carbon (C) has an atomic number of 6 (1s² 2s² 2p²) and is located to the right of beryllium in the periodic table.
- As we move from left to right across a period, the ionization energy increases due to increased effective nuclear charge.
- Therefore, carbon will have a higher ionization enthalpy than beryllium.
- **Conclusion**: This statement is **correct**.

5. **Analyzing Statement (4): F > Ne**:
- Fluorine (F) has an atomic number of 9 (1s² 2s² 2p⁵) and neon (Ne) has an atomic number of 10 (1s² 2s² 2p⁶).
- Neon has a completely filled outer shell, making it very stable and requiring a large amount of energy to remove an electron.
- Therefore, neon will have a higher ionization enthalpy than fluorine.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion:
The correct orders of ionization enthalpy are found in statements (1) and (3). Therefore, the correct answer is statements **(1) and (3)**.