Question

Which of the following are pairs of isotones?

• A. ${}^{37}Cl$ and ${}^{39}K$
• B. ${}^{15}N$ and ${}^{16}O$
• C. ${}^{14}C$ and ${}^{12}C$
• D. Both A and B

Answer 1

The correct option is D Both A and B

Isotones have same number of neutrons.
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Number of neutrons for ${}^{39}K=A-Z=39-19=20$
Number of neutrons for ${}^{37}Cl=A-Z=37-17=20$

Number of neutrons for ${}^{16}O=A-Z=16-8=8$
Number of neutrons for ${}^{15}N=A-Z=15-7=8$

Number of neutrons for ${}^{14}C=A-Z=14-6=8$
Number of neutrons for ${}^{12}C=A-Z=12-6=6$

Hence, $a$ and $b$ are pairs of isotones.