B has a smaller first ionization enthalpy than Be. The correct statements are:

(I) It is easier to remove 2p electron than 2s electron.
(II) 2p electron of B is more shielded from the nucleus by the

Question

B has a smaller first ionization enthalpy than Be. The correct statements are:

(I) It is easier to remove 2p electron than 2s electron.
(II) 2p electron of B is more shielded from the nucleus by the inner core of electrons than the 2s electrons of Be.
(III) 2s electron has more penetration power than 2p electron.
(IV) Atomic radius of B is more than Be.

(JEE Main, 09 Jan 2020)

Canvas Classes · Accepted Answer

Strategy:
 Beryllium (, ) and Boron (, ) exhibit an  anomaly based on orbital penetration and shielding.

Step 1: Evaluate Statements
- (I): The  electron is further from the nucleus and in a higher energy subshell than the  electrons. (Correct)
- (II): The  electron of B is shielded by the inner  core and the  subshell. The  electrons of Be are only shielded by the  core. (Correct)
- (III): An -electron penetrates closer to the nucleus and is more strongly attracted than a -electron of the same

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