Answer: Ten electrons in total
Explanation: In a 3d sublevel, there are five orbitals . Two electrons can be put in one orbital.
Thus 5 orbitals can occupy 10 electrons .
Just like 1s orbital can occupy 2 electrons and 2p orbital can occupy total of six electrons in 3 orbitals.
Thus, the electronic configurton of Zinc , having atomic number 30 is
Zinc (Zn) = 1s2 2s2 2p6 3s2 3p6 4s2 3d10