Question

The subshells filled one by one for 3 period elements are 1) 3s 3d 3p 2) Is 3d up 3) 3s 3p​

Answer 1

Explanation:

I think its option 3. 3s 3p

Answer 2

The correct answer will be option 3.

The electrons are filled according to  Aufbaus' principle.

Aufbaus' principles state that the filling of electrons should be based on energy levels.  First, the electron should enter lower energy shells and then the higher energy shells.

The energy of the subshells is 1s 2s 2p 3s 3p 4s

So, according to the sequence the electron will first be filled in the 3s subshell and then the 3p subshell.