Question

In comparison to boron, berylium has

• A. lesser nuclear charge and lesser first ionisation enthalpy
• B. greater nuclear charge and lesser first ionisation enthalpy
• C. greater nuclear charge and greater first ionisation enthalpy
• D. lesser nuclear charge and greater first ionisation enthalpy

Answer 1

The correct option is D lesser nuclear charge and greater first ionisation enthalpy

In comparision to boron, beryllium has lesser nuclear charge and greater first ionisation enthalpy.
Electronic configuration of $Be\left(4\right)=1s^2,2s^2$
It possess completely filled $s-$ orbitals. Hence, high amount of energy is required to pull the electron from the gaseous atom. Beryllium (4) lies left of the boron (5) and on moving from left to right an electron is added due to which nuclear charge increases from $Be$ to $B$.