Isodiaphers are a specific classification of nuclides in radiochemistry. Which of the following pair — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Isodiaphers must have the same $(A - 2Z)$ or $(N - Z)$ value. For $U-235$: $235 - 2(92) = 51$ and $Th-231$: $231 - 2(90) = 51$ (Pair A is valid). For $K-39$: $39 - 2(19) = 1$ and $F-19$: $19 - 2(9) = 1$ (Pair B is valid). For $Cu-65$: $65 - 2(29) = 7$ and $Cr-55$: $55 - 2(24) = 7$ (Pair C is valid). For $C-14$ and $N-14$, they have the same mass number but different isotopic numbers (2 vs 0), making them isobars, not isodiaphers.