Which pair of nuclides are isotones (same neutron number)?

Question

G1 Physics · Accepted Answer

Step 1: Isotones have the same number of neutrons, N = A − Z. Step 2: For Se-74, N = 74 − 34 = 40. For Ga-71, N = 71 − 31 = 40. Final answer: Option A, both nuclei have 40 neutrons.