Question

From the given examples from the pair of isotopes and the pair of isobars.
${}_{18}^{40}Ar,{}_{17}^{35}Cl,{}_{20}^{40}Ca,{}_{17}^{37}Cl$

Answer 1

Isotopes are those which has a same atomic number but different mass number whereas isobars are those which have a different atomic number but the same mass number.

Here, ${}_{17}^{35}Cl$ and ${}_{17}^{37}Cl$ are isotopes where as ${}_{18}^{40}Ar$ and ${}_{20}^{40}Ca$ are isobars.