In the ground state electron configuration of zinc (Zn), how many electrons occupy the 3d sublevel?

• A. 2
• B. 10
• C. 8
• D. 6

Answer: (B)

Verified step by step guidance

1. Identify the atomic number of zinc (Zn), which tells you the total number of electrons in a neutral atom. Zinc has an atomic number of 30, so it has 30 electrons.
2. Recall the order in which electron sublevels are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, then 3d.
3. Write out the electron configuration step-by-step until you reach 30 electrons: fill 1s (2 electrons), 2s (2 electrons), 2p (6 electrons), 3s (2 electrons), 3p (6 electrons), 4s (2 electrons), and then place the remaining electrons in the 3d sublevel.
4. Count how many electrons are placed in the 3d sublevel after filling the 4s sublevel. Since 4s fills before 3d, the remaining electrons after filling 4s will go into 3d.
5. Conclude that the 3d sublevel in zinc's ground state electron configuration contains 10 electrons, as it is fully filled.