Question

From the given examples, form the pair of isotopes and the pair of isobars:
${}_{18}A{r}^{40}{,}_{17}C{l}^{35}{,}_{20}C{a}^{40}{,}_{17}C{l}^{37}$

Answer 1

$I)$ Isotopes have same atomic number but different mass number. ${17}^{{Cl}^{35}}{17}^{{Cl}^{37}}$ are isotopes.

$II)$ Isobars have same mass number but different atomic number. ${18}^{A{r}^{40}}\&{17}^{{Cl}^{37}}$ are isobars