Two atoms have the same atomic mass but different atomic numbers. Such atoms are called as:

Identify the isoelectronic species from the following groups.

The electronic configuration of a dipositive metal $M^{2+}$ is $2, 8, 14$ and its atomic weight is $56 \ a.m.u.$ The number of neutrons in its nuclei would be

The symbol of an isotope is $_{32}X^{65}$,this reveals that

Which of the following species does not have the same number of electrons as the other three species?

When a sulphur atom becomes a sulphide ion,