Question

Which of the following are isotopes and which are isobars ?

Argon, Deuterium, Calcium, Tritium, Protium

Answer 1

Deuterium $\left({}_1{}^2\mathrm{H}\right)$, protium $\left({}_1{}^1\mathrm{H}\right)$ and tritium $\left({}_1{}^3\mathrm{H}\right)$ are isotopes of hydrogen.

${}_{18}{}^{40}\mathrm{Ar}\mathrm{and}{}_{20}{}^{40}\mathrm{Ca}$ (Argon and Calcium, respectively) are isobars with same mass number but different atomic numbers.