Recall that the * quantum numbers* that define an electron are:

• *Principal Quantum Number***(n)**: deals with the size and energy of the atomic orbital. The possible values for n are **1 to ∞**.

• *Angular Momentum Quantum Number ***(l)**: deals with the shape of the atomic orbital. The possible values for l are **0 to n – 1**.

• *Magnetic Quantum Number ***(m**_{l}**)**: deals with the orientation of the atomic orbital in 3D space. The possible values for m_{l} are the range of **–l to +l**.

Which of the following indicates an orbital in the third energy level?

a) 3s

b) 5f

c) 4d

d) 2p