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238U is radioactive. One of the intermediates in its decay is obtained via 3 alpha emissions, 2 beta emissions and 3 gamma emissions. What is the identity of this intermediate? (You may consult a Periodic Table)
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Correct Answer: D. 22688Ra
Equation I: 23892U -> xyZ + 342He + 20-1e– + 3 (gamma rays)
Since the sum of the atomic numbers and mass numbers on either side of the equation must be equal:
238 = x + (3 x 4) + (2 x 0) + (3 x 0)
x = 226
92 = y + (3 x 2) + (2 x -1) + (3 x 0)
y = 88
Thus, from the answer choices, Z = Ra; note that gamma rays are a form of electromagnetic radiation and thus have no charge and no mass.
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