Select the pair of atoms having the same number of electrons in their outermost shell.

Which subatomic particle has negligible mass?

When alpha particles are bombarded on thin gold foil, most of the alpha particles pass through straight because 

The relative atomic masses of some elements are not whole numbers because of

The mass of neutron is nearly the same as that of

Lithium has $3$ electrons, $4$ neutrons, $3$ protons. Its mass number is 

${}_6{}^{13}\mathrm{C}$ and ${}_6{}^{12}\mathrm{C}$ differ from each other in respect to the number of 

${}_{32}{}^{76}\mathrm{Ge}$ is isotonic with