First ionisation enthalpy of Be is higher than B.(T/F)

Answer

To determine whether the statement "First ionisation enthalpy of Be is higher than B" is true or false, we can analyze the electronic configurations and the factors affecting ionisation enthalpy.

### Step-by-Step Solution:

1. **Identify Atomic Numbers**:
- Beryllium (Be) has an atomic number of 4.
- Boron (B) has an atomic number of 5.

2. **Write Electronic Configurations**:
- The electronic configuration of Beryllium (Be) is:
\[ 1s^2 \, 2s^2 \]
- The electronic configuration of Boron (B) is:
\[ 1s^2 \, 2s^2 \, 2p^1 \]

3. **Analyze the Stability of Electronic Configurations**:
- Beryllium has a completely filled outer shell (2 electrons in the 2s subshell).
- Boron has one electron in the 2p subshell, which is not fully filled.

4. **Consider Ionisation Enthalpy**:
- Ionisation enthalpy is the energy required to remove an electron from an atom.
- Atoms with a fully filled subshell (like Beryllium) are generally more stable and require more energy to remove an electron compared to atoms with partially filled subshells (like Boron).

5. **Conclusion**:
- Since Beryllium has a fully filled configuration, it has a higher first ionisation enthalpy than Boron, which has an unpaired electron in the 2p subshell.
- Therefore, the statement "First ionisation enthalpy of Be is higher than B" is **True**.

### Final Answer:
**True**