What is the maximum number of electrons in the first shell?

• A. 8
• B. 2
• C. 32
• D. 18

Answer: (B)

Electrons are arranged in shells with a maximum capacity given by 2n^2, where n is the shell number. For the first shell, n = 1, so 2(1)^2 = 2 electrons. There is only one orbital in this shell (the 1s orbital), and it can hold two electrons with opposite spins due to the Pauli exclusion principle. This is why the first shell’s maximum is two. The other numbers correspond to higher shells (second shell can hold up to 8, third up to 18, fourth up to 32), which is why they don’t apply to the first shell.