Question

The triad of nuclei that is isotonic is

• A. ${}_6{N}^{14},{}_7{N}^{14},9F^{19}$
• B. ${}_6{C}^{14},{}_7{N}^{15}{}_{,9}{F}^{17}$
• C. ${}_6{C}^{14},{}_{,7}{N}^{14},9F^{17}$
• D. ${}_6{C}^{12},{}_7{N}^{14},{}_{,9}{F}^{19}$

Answer 1

Answer: (B)

Isotonic species are defined as the species which have the same number of neutrons.
No. of neutrons in:
${}_6{C}^{14}=14-6=8$
${}_7{N}^{14}=14-7=7$
${}_9{F}^{19}=19-9=10$
${}_7{N}^{15}=15-7=8$
${}_9{F}^{17}=15-7=8$
${}_6{C}^{12}=12-6=6$
${}_6{C}^{14},{}_7{N}^{15},{}_9{F}^{17}$ are isotonic species.