Question

The electron configuration of calcium is
A. 1s22s22p23s23p34s2.
B. 1s22s22p103s23p4.
C. 1s22s23s23p63d8.
D. 1s22s22p63s23p64s2.
???

Answer 1

20 Ca :

1s², 2s², 2p⁶, 3s², 3p⁶, 4s²

Answer D

hope this helps!

Answer 2

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