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

The sum of paired electrons present in $l = 2$ orbitals for the species $Fe^{2+}$,$Co^{2+}$,and $Ni^{2+}$ is .......

Which of the following elements has the least number of electrons in its $M$ shell?

Which of the following sets of quantum numbers is consistent with the rules of quantum mechanics?

What is the maximum number of electrons with the same spin that can be accommodated in a shell with principal quantum number $n$?

The general configuration of the outermost and penultimate shell is $(n - 1)s^2 (n - 1)p^6 (n - 1)d^x ns^2$. If $n = 4$ and $x = 5$,then the number of protons in the nucleus will be: