Question

which orbital is lower in energy in a many-electron atom?
○ 3s
○ 4s

Explanation:

In a many - electron atom, the energy of an orbital is related to its principal quantum number (\(n\)) and angular momentum quantum number (\(l\)). The principal quantum number \(n\) has a major influence on the energy level. For \(s\) orbitals, as the value of \(n\) (the principal quantum number) increases, the energy of the orbital generally increases. The \(3s\) orbital has \(n = 3\) and the \(4s\) orbital has \(n=4\). Since \(3<4\), the \(3s\) orbital has lower energy than the \(4s\) orbital.

Answer:

\(3s\) (i.e., the option with "3s")