Question

In boron atom screening on outermost electron is due to:

• A. electrons of K shell only
• B. all the electrons of K and L shell
• C. two electrons of 1s and 2s each
• D. only by electrons of L shell

Answer 1

The correct option is C two electrons of 1s and 2s each

Boron $=1S^{2}2S^{2}2P^1$

Screening effect :- Higher is the screening electron causes less attraction from the nucleus and can be easily removed, which leads to lower value of ionisation potential.

To Screening effect in Boron in Boron is due to two electrons of $1S$ and $2S$ subshells.