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Question:

In comparison to boron, beryllium has:

lesser nuclear charge and greater first ionisation enthalpy

lesser nuclear charge and lesser first ionisation enthalpy

greater nuclear charge and lesser first ionisation enthalpy

greater nuclear charge and greater first ionisation enthalpy

Solution:

Correct option is A. lesser nuclear charge and greater first ionisation enthalpy. In case of 'Be' electron remove from '2s' orbital while in case of 'B' electron remove from '2p' orbital. '2s' orbital have greater penetration effect then '2p' orbitals. So, 'Be' having more IE then 'B'.