Which of the following orbitals has two angular nodes?

The electrons,identified by quantum numbers $n$ and $l$ as $(i) n = 4, l = 1$,$(ii) n = 4, l = 0$,$(iii) n = 3, l = 2$,$(iv) n = 3, l = 1$,can be placed in order of increasing energy,from the lowest to highest,as:

The minimum number of quantum numbers required to specify an orbital in an atom is

The number of unpaired electrons in $Ni$ (atomic number $= 28$) is:

Energy of atomic orbitals in a particular shell is in the order

The magnetic quantum number for the valence electron of sodium is