Question

Which one is/are pair of isotopes?

Options

• \[ {}^{12}_{\phantom{1}6}\mathrm{C} \text{ and } {}^{14}_{\phantom{1}6}\mathrm{C} \]

• \({ }_{11}^{24} \mathrm{Na}\) and \({ }_{12}^{24} \mathrm{Mg}\)

• \[ {}^{17}_{\phantom{1}8}\mathrm{O} \text{ and } {}^{16}_{\phantom{1}8}\mathrm{O} \]

• both \[({}^{12}_{\phantom{1}6}\mathrm{C}, {}^{14}_{\phantom{1}6}\mathrm{C})\] and \[( {}^{17}_{\phantom{1}8}\mathrm{O}, {}^{16}_{\phantom{1}8}\mathrm{O})\]

Answer 1

Both \[({}^{12}_{\phantom{1}6}\mathrm{C}, {}^{14}_{\phantom{1}6}\mathrm{C})\] and \[( {}^{17}_{\phantom{1}8}\mathrm{O}, {}^{16}_{\phantom{1}8}\mathrm{O})\]

Explanation:

\[ {}^{12}_{\phantom{1}6}\mathrm{C} \text{ and } {}^{14}_{\phantom{1}6}\mathrm{C} \] both have Z = 6, and \[ {}^{17}_{\phantom{1}8}\mathrm{O} \text{ and } {}^{16}_{\phantom{1}8}\mathrm{O} \] both have Z = 8.

Therefore, both pairs are isotopes.

\({ }_{11}^{24} \mathrm{Na}\) and \({ }_{12}^{24} \mathrm{Mg}\) have the same mass number, so they are isobars.