erick862
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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