Question

Which of the following is/are example(s) of isotones?

• A. ${}_6{C}^{12}$ and ${}_6{C}^{13}$
• B. ${}_{11}N{a}^{23}$ and ${}_{12}M{g}^{23}$
• C. ${}_{14}S{i}^{30}$ and ${}_{16}{S}^{32}$
• D. ${}_{83}B{i}^{210}$ and ${}_{84}P{o}^{210}$

Answer 1

The correct option is C ${}_{14}S{i}^{30}$ and ${}_{16}{S}^{32}$

Atoms having same number of neutrons, A Z (number of nucleons number of protons) but different number of protons or electrons, Z are called isotones. For ${}_{14}S{i}^{30}$ & ${}_{16}{S}^{32}$ the atomic and mass number of Si is $14$ and $30$ respectively and that of S is $16$ and $32$.
Thus for ${}_{14}S{i}^{30}$, number of protons $=Z=14$ and number of neutrons $=A-Z=30-14=16$.
For ${}_{16}{S}^{32}$, number of protons $=Z=16$ and number of neutrons $=A-Z=32-16=16$.