Beryllium has higher ionisation enthalpy than boron.This can be explained as,
A. Beryllium has higher size than boron hence its ionisation enthalpy is higher
B. Penetration of 2p-electrons to the nucleus is more than the 2s-electrons
C. It is easier to remove electron from 2p-orbital as compared to 2s-orbital due to more penetration of s-electrons
D. Ionisation energy increases in a period.
