$A$ certain orbital has no angular nodes and two radial nodes. The orbital is

Which of the following sets of quantum numbers is impossible for an electron?

The electronic configurations of four elements are given in brackets: $L\,(1s^2, 2s^2 2p^1)$; $M\,(1s^2, 2s^2 2p^5)$; $Q\,(1s^2, 2s^2 2p^6, 3s^1)$; $R\,(1s^2, 2s^2 2p^2)$. Which element would most readily form a diatomic molecule?

The principal quantum number of an atom is related to the:

The orientation of an atomic orbital is governed by

What is the decreasing order of energy for the $2s$-orbital of $H, Li, Na$,and $K$ atoms?