Question

The triad of nuclei that are isotonic is:

• A. ${}_6^{14}C,{}_7^{15}N,{}_9^{17}F$
• B. ${}_6^{12}C,{}_7^{14}N,{}_9^{19}F$
• C. ${}_6^{14}C,{}_7^{14}N,{}_9^{17}F$
• D. ${}_6^{14}C,{}_7^{14}N,{}_9^{19}F$

Answer 1

The correct option is A ${}_6^{14}C,{}_7^{15}N,{}_9^{17}F$

Isotones are species that have the same number of neutrons but a different number of protons.
Number of neutrons = mass number – atomic number
Number of neutrons in ${}_6^{14}C$ = 14 – 6 = 8
Number of neutrons in ${}_7^{15}N$ = 15 – 7 = 8
Number of neutrons in ${}_9^{17}F$ = 17 – 9 = 8