Answer:
8 electrons
Step-by-step explanation:
The atomic number of calcium (ca) is 20. Therefore,
in the first shell the number of electrons are 2
in second shell the number of electrons are 8
in the third shell the number of electrons are 8
in the fourth shell the number of electrons are 2
electronic configuration in ground state:
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2
Hope it helps u (｡◕‿◕｡)