In the quantum mechanical picture of the hydrogen atom, the orbital angular momentum of the electron may be zero in any of the possible energy states. For which energy state must the orbital angular momentum be zero?

Question

In the quantum mechanical picture of the hydrogen atom, the orbital angular momentum of the electron may be zero in any of the possible energy states. For which energy state must the orbital angular momentum be zero? 
n = 1
n = 2
n = 3
n = 4 
Give your reasoning.

I am not sure about this one but I think the answer is 2 but I am unsure why. Please explain.

drwls · Answer

The key word in that question is MUST. The correct answer is 1. See my answer to your previous question.