Question

When the 3d orbital is complete, the new electron will enter in:

• A. 4p-orbital
• B. 4f orbital
• C. 4s orbital
• D. 4d-orbital

Answer 1

Answer: (A)

According to the Aufbau principle of electron filling in orbitals, the next shell to be filled after the $3d$ orbital is the $4p$ orbital.

Hence, the correct option is $\text{A.}$