What is the relationship between the shapes of $3d_{xy}$ and $3d_{x^2-y^2}$ orbitals?

Beryllium's fourth electron will have the four quantum numbers :

The extra stability of half-filled subshells is due to:
$(A)$ Symmetrical distribution of electrons
$(B)$ Smaller coulombic repulsion energy
$(C)$ The presence of electrons with the same spin in non-degenerate orbitals
$(D)$ Larger exchange energy
$(E)$ Relatively smaller shielding of electrons by one another
Identify the correct statements.

The number of angular and radial nodes of $4d$ orbital respectively are

The number of unpaired electrons in an atom with atomic number $29$ is .....

Which of the following elements contains the maximum number of unpaired electrons?