The atomic number of an element is $35$ and its mass number is $81$. The number of electrons in the outermost shell is:

The atomic numbers of elements $X, Y$ and $Z$ are $19, 21$ and $25$ respectively. The number of electrons present in the $M$-shell of these elements follow the order:

Which of the following orbitals has/have zero probability of finding the electron in the $xy$ plane?

For a magnetic quantum number $m = 0, \pm 1$,the value of the principal orbital (azimuthal quantum number $l$) corresponds to which subshell,and what is the minimum principal quantum number $n$ required for this set?

Arrange the energy of the $2s$ orbital in the following atoms in decreasing order: $H, Li, Na, K$.

The atomic weight of an element is twice its atomic number. If the $2p$ subshell contains three electrons,the element is .......