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MHT CET 2020 (16 Oct, Shift 2) · Radioactive Decays: Alpha, Beta, Gamma

Radioactive Decays: Alpha, Beta, Gamma question from MHT CET 2020 (16 Oct, Shift 2)

Q20MHT CET 2020 · 16 OCT · SHIFT 2Medium

Radioactive Decays: Alpha, Beta, Gamma

A radioactive nucleus emits 4α4\alpha-particles and 7β7\beta-particles in succession. The ratio of number of neutrons of that of protons, is [A=A = mass number, Z=Z = atomic number]

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Answer: (b)

  1. 4α4\alpha: A′=A−16A' = A - 16, ΔZ=−8\Delta Z = -8. 7β−7\beta^-: ΔZ=+7\Delta Z = +7.
  2. Protons: Z′=Z−8+7=Z−1Z' = Z - 8 + 7 = Z - 1.
  3. Neutrons: A′−Z′=A−16−(Z−1)=A−Z−15A' - Z' = A - 16 - (Z - 1) = A - Z - 15.
  4. Ratio =A−Z−15Z−1= \dfrac{A-Z-15}{Z-1}, so the answer is (b).
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