Chemistry (12th Grade)
Electron Configuration
What is the electron configuration of calcium (Ca)?
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p6
1s2 2s2 2p6 3s2 3p6 4s2
1s2 2s2 2p6 3s2 3p6 4s1