Respuesta :
The element X which is involved in the given nuclear reaction is ²³⁵₉₂U.
What is radio active decay?
Radio active decay is a process in which an unstable nuclei will emit some particles from the nuclei in the form of energy to get stability.
In the given chemical reaction, parent nuclei (²³⁹₉₄Pu) will emit the alpha particle (⁴₂He) which has a atomic number 2 and atomic mass of 4 as a result of which we get a daughter nuclei Uranium which will get the atomic number 92 and atomic mass of 235.
²³⁹₉₄Pu → ⁴₂He + ²³⁵₉₂U
Hence the element X is uranium (²³⁵₉₂U).
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