Question

State the electronic configuration for argon? [$p=18,n=22$]

• A. $2,8,5$
• B. $2,8,6$
• C. $2,8,7$
• D. $2,8,8$

Answer 1

The correct option is D $2,8,8$

As we know, atomic number is the total number of proton present in nucleus of an atom and atomic mass number is the total number of proton and neutron.
So Ar have atomic number $18$ and mass number $18+22=40$. So K shell will accommodate $2$ electrons. L shell can accommodate $8$ electrons. Remaining $8$ electrons will be accommodated in M shell.