A radioactive element A decays into radioactive element C by the following processes in succession. A → B + ₂He⁴; B → C + 2e⁻ Then elements (a) A and B are isobars. (b) A and C are isobars. (c) A and C are isotopes. (d) A and B are isotopes.

Answer: (c). α emission: A → A-4, Z → Z-2, so B has (A-4, Z-2). Two β⁻ emissions: Z increases by 2, A unchanged, so C has (A-4, Z). A and C have the same Z but different A, so they are isotopes. So the answer is (c) A and C are isotopes.

A radioactive element A decays into radioactive element C by the… | MHT CET 2025 (22 Apr, Shift 2)

Q4MHT CET 2025 · 22 APR · SHIFT 2Easy

Radioactive Decays: Alpha, Beta, Gamma

A radioactive element A decays into radioactive element C by the following processes in succession.

$\text{A} \rightarrow \text{B} + {}_{2}\text{He}^{4};\ \text{B} \rightarrow \text{C} + 2\text{e}^{-}$ Then elements

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Answer: (c)

$\alpha$ emission: $A \to A-4$ , $Z \to Z-2$ , so B has $(A-4,\ Z-2)$ .
Two $\beta^-$ emissions: $Z$ increases by 2, $A$ unchanged, so C has $(A-4,\ Z)$ .
A and C have the same $Z$ but different $A$ , so they are isotopes.
So the answer is (c) A and C are isotopes.

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Radioactive Decays: Alpha, Beta, Gamma question from MHT CET 2025 (22 Apr, Shift 2)

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