The set of quantum numbers for the outermost electron for copper $(Cu)$ in its ground state is:

Total number of angular nodes of orbitals associated with third shell $(n=3)$ of an atom is

The spin of the electron:

Consider the following statements :
$(a)$ Electron density in the $xy$ plane in $3d_{x^2-y^2}$ orbital is zero.
$(b)$ Electron density in the $xy$ plane in $3d_{z^2}$ orbital is zero.
$(c)$ $2s$ orbital has one nodal surface.
$(d)$ For $2p_z$ orbital,$yz$ is the nodal plane.
Select the incorrect statements $:-$

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

While filling up of electrons in the atomic orbitals,the $4s$ orbital is filled before the $3d$ orbital,but the reverse happens during the ionization of the atom. Explain why?