In a multi-electron system,the energy of an electron of $2p_y$ orbital is :-

The electronic configuration of a nitrogen atom in its ground state is represented as follows:

The number of unpaired electrons in the excited state of carbon is equal to the number of unpaired electrons in which of the following?

The presence of three unpaired electrons in a nitrogen atom is explained by .......

Arrange the following orbitals in increasing order of energy based on the given values of principal quantum number $(n)$ and azimuthal quantum number $(l)$:
$(1) n = 4, l = 1$
$(2) n = 4, l = 0$
$(3) n = 3, l = 1$
$(4) n = 3, l = 2$

Which among the following elements possesses one electron in the $4s$ orbital in its observed electronic configuration?