Which of the following pairs of nuclear species correctly represents "isodiaphers"? — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Isodiaphers are atoms that have the same isotopic number, which is defined as the difference between neutrons and protons ($N - Z$ or $A - 2Z$). An element and its daughter product after an $\alpha$ -decay are always isodiaphers. For U-235: $235 - 2(92) = 51$. For Th-231: $231 - 2(90) = 51$. Both share an isotopic number of 51.