An element has an atomic mass of $19$ and an atomic number of $9$. How can its ion be represented?

The electronic configuration of a divalent metal ion $M^{2+}$ is $2, 8, 14$ and its atomic mass is $58 \, a.m.u.$ What is the number of neutrons in its nucleus?

$A$ sodium cation $(Na^+)$ has a different number of electrons from which of the following species?

The group having isoelectronic species is:

Calculate the number of protons,neutrons and electrons in $_{35}^{80}Br$.

The composition of tritium $(_{1}H^{3})$ is: