Question

What is the electron configuration of an element with atomic number 20?

A. 1s^2 2s^2 2p^6 3s^2 3p^5

B. 1s^2 2s^2 2p^6 3s^2 3p^6

C. 1s^2 2s^2 2p^6 3s^2

D. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2

E. 1s^2 2s^2 2p^6

Answer 1

its d

Step-by-step explanation:

Answer 2

answer: D

Step-by-step explanation:

according to the aufbau principle the electrons should be filled