Q. Which of the following is correct?
A) $\ _{1}H^{1}\$and $\ _{2}He^{3}$ are isotopes
B) $\ _{6}C^{14}$ and $\ _{7}N^{14}$ are isotopes
C) $\ _{19}K^{39}$ and $\ _{20}Ca^{40}$ are isotones
D) $\ _{9}F^{19}$ and $\ _{11}Na^{24}$ are isodiaphers
Explanation
(c)
Isotones are species which have equal number of neutrons.
Neutrons in $\ _{19}K^{39} = 39 - 19 = 20$
Neutrons in $\ _{20}Ca^{40} = 40 - 20 = 20$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.