In the uranium radioactive series, the initial nucleus is ²³⁸₉₂U and the final nucleus is ²⁰⁶₈₂Pb. Find the numbers of α-particles and β⁻-particles emitted.
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In the uranium radioactive series, the initial nucleus is ²³⁸₉₂U and the final nucleus is ²⁰⁶₈₂Pb. Find the numbers of α-particles and β⁻-particles emitted.

G1 Physics · Accepted Answer

Let Nα be the number of α decays and Nβ the number of β⁻ decays. Mass number: 238 − 4Nα = 206, so Nα = 8. Atomic number after 8 α decays is 92 − 16 = 76. Each β⁻ decay increases Z by 1, so 76 + Nβ = 82. Hence Nβ = 6. Correct answer: B.