Consider the ground state of Cr atom (Z = 24). The numbers of electrons with the azimuthal quantum numbers, l = 1 and 2 are, respectively

The electronic configuration of Cr  in ground state is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{5}4{\mathrm{s}}^1$

l=1 represents 'p-orbitals'

1=2 represents 'd-orbitals'

Thus the number of electrons with l=1 is 12

and the number of electrons with l=2 is 5