Q. The nuclei of which one of the following pairs of nuclei are isotones ?
A) ⁷⁴₃₄Se, ⁷¹₃₁Ga
B) ⁹²₄₂Mo, ⁹²₄₀Zr
C) ⁸⁴₃₈Sr, ⁸⁶₃₈Sr
D) ⁴⁰₂₀Ca, ³²₁₆S
Explanation
[Solution from source] Isotones have the same neutron number N = A − Z. Se: 74 − 34 = 40; Ga: 71 − 31 = 40. The Sr pair are isotopes (same Z) and the Mo/Zr pair are isobars (same A). Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.