Isotopes have identical chemical properties in their ions

Steps:

• Recognize ^{32}X and ^{35}X as isotopes of the same element X, sharing the same atomic number Z but differing in mass numbers.
• Note both are -1 ions, so each has Z + 1 electrons, yielding identical electron configurations.
• Recall chemical properties depend solely on electron configuration, not nuclear composition.
• Conclude the ions exhibit the same chemical behavior despite isotopic differences.

Why A is correct:

• By definition, isotopes of an element have the same electron configuration in corresponding ions, resulting in identical chemical properties.

Why the others are wrong:

• B: Both ions have the same number of electrons (Z + 1).
• C: Neutrons differ (32 - Z vs. 35 - Z).
• D: Protons are the same (both have atomic number Z).

Final answer: A