Which sequence of ionisation potential is correct?

Options

A. `B lt Be `
B. `Be lt B `
C. `Be = B `
D. None of these

Answer

To determine the correct sequence of ionization potentials for the given elements, we will analyze the ionization energies of beryllium (Be) and boron (B) based on their electronic configurations.

### Step-by-Step Solution:

1. **Understanding Ionization Potential**:
- Ionization potential (or ionization energy) is the energy required to remove an electron from an atom in its gaseous state. The higher the ionization potential, the more energy is needed to remove an electron.

2. **Identify the Elements**:
- We are comparing beryllium (Be) and boron (B).
- Beryllium has an atomic number of 4, and its electronic configuration is \(1s^2 2s^2\).
- Boron has an atomic number of 5, and its electronic configuration is \(1s^2 2s^2 2p^1\).

3. **Analyze the Electronic Configurations**:
- Beryllium has a full outer shell configuration with 2 electrons in the 2s orbital.
- Boron has a configuration with 3 electrons in the outer shell (2 in the 2s and 1 in the 2p).

4. **Comparing Ionization Energies**:
- Removing an electron from beryllium (which has a stable filled 2s orbital) requires more energy compared to removing an electron from boron (which has an unpaired electron in the 2p orbital).
- The filled 2s orbital in beryllium is more stable than the 2p electron in boron, making it harder to remove an electron from beryllium.

5. **Conclusion**:
- Therefore, the ionization potential of beryllium is higher than that of boron.
- The correct sequence of ionization potentials is:
\[ \text{Ionization Potential of Be} > \text{Ionization Potential of B} \]

### Final Answer:
The correct sequence of ionization potential is:
\[ \text{IP(Be)} > \text{IP(B)} \]