In the $n^{th}$ quantum level,the number of electronic subshells is

What is the electronic configuration of $Cu$?

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 represents:

The set of quantum numbers not applicable for an electron in an atom is

Based on the quantum numbers, what will be the maximum number of elements in the sixth period of the periodic table?