What is the maximum number of electrons that can be placed in the first shell/energy level?
A. 1
B. 8
C. 2
D. 18

Answer:
D. 18
Explanation:
Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on.