Principal Quantum Number — Prelims Questions

Which of the following statements about the Principal Quantum Number (n) is INCORRECT?

An electron is in the M-shell. What is the value of its Principal Quantum Number (n)?

What is the maximum number of electrons that can be accommodated in the N-shell?

Which of the following sets of quantum numbers is NOT possible?

Which of the following orbitals has the highest energy in a multi-electron atom?

An electron in a hydrogen atom transitions from an excited state with $n=3$ to the ground state with $n=1$. What is the energy of the emitted photon? (Given: Rydberg constant $R_H = 2.18 \times 10^{-18}$ J)