Which of the following is a possible noble gas notation? [ar] 4s24p2 [ar] 3s23p6 [ar] 4s23d104p2 [ar] 3s23d10

Option (c) is the correct answer.

Explanation:

According to Aufbau's principle, in the ground state of an element, electrons first enter into the lowest energy level before entering into higher energy level.

It is known that an "s" sub-shell has lower energy than a "p" sub-shell so, s shell will fill first and then p shell will be filled.

For example, a noble gas notation shows that 4s shell will be filled first as it has lower energy then 3d shell will be filled as 3d shell has less energy as compared to a 4p shell.

Thus, we can conclude that out of the given options is a possible noble gas notation.

i do not get it   at all