The shape of $d_{xy}$ orbital will be

What is the total number of unpaired electrons present in the observed electronic configuration of $Cr$ $(Z=24)$?

Statement $A$: In a potassium atom,the $19^{th}$ electron enters the $4s$-orbital instead of the $3d$-orbital.
Reason $R$: The $(n + l)$ rule is followed to determine the minimum energy of an orbital.

Which of the following sets of quantum numbers is correct for an electron in a $4f$ orbital?

Which of the following is not a permissible arrangement of electrons in an atom?

What is the atomic number of the element with $M^{2+}$ ion having electronic configuration $[Ar] 3d^8$?