Question

Which of these are pairs of isobar?

• A. ${}_6{C}^{12},{}_8{O}^{16}$
• B. ${}_6{C}^{13},{}_6{O}^{14}$
• C. ${}_{20}C{a}^{40},{}_{18}A{r}^{40}$
• D. None of these

Answer 1

Answer: (C)

${}_{20}C{a}^{40},{}_{18}A{r}^{40}$

Isobars have the same atomic mass number and different atomic number.

Out of given options, the pair is option 'C'.

${}_{20}{Ca}^{40},{}_{18}{Ar}^{40}$, both have same atomic mass number and have different atomic numbers.

Hence, ${}_{20}{Ca}^{40}{,}_{18}{Ar}^{40}$ are isobars .

Thus, the correct answer is 'C'.