Identify the element if its expected electronic configuration is $[Ar] 3d^{10} 4s^{2}$.

In which of the following pairs of orbitals is the probability of finding the electron zero in the $XY$ plane?

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

In a potassium atom,the electronic energy levels are in the following order:

In which of the following species,the ratio of $s$-electrons to $p$-electrons is the same?

The atomic number of an element is $35$. What is the total number of electrons present in all the $p-$ orbitals of the ground state atom of that element?