Question:
In comparison to boron, berylium has :
Correct Option: , 4
Solution:
Nuclear charge : $\mathrm{B}>\mathrm{Be}$
$\mathrm{Be}=1 s^{2} 2 s^{2}$ (more stable)
$\mathrm{~B}=1 s^{2} 2 s^{2} 2 p^{1}$
$\therefore$ Ionisation energy of Be is greater than B due to $n s^{2}$ outer electronic configuration.