What is the total number of electrons in the second energy shell of a calcium atom in the ground state

8 electrons

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

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nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.