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Title: What was the original element? Post by: Annonn on Apr 12, 2022 An element undergoes the following sequence of decay reactions: alpha, beta, alpha, beta, alpha and produces radium-223. What was the original element?
238U 227Th 231Pa 231Th 235U Title: Re: What was the original element? Post by: Woo on Apr 13, 2022 we have 3 alpha decays, which reduces to proton by a count of 2 and atomic mass by 4 each time. beta increases the proton count by 1, but leaves the atomic mass the same.
radium-223 has a mass of 223 and 88 protons. 88 + 2 + 2 + 2 - 1 - 1 = 92 -- uranium 235U is the answer |