Question

a nucleus 238u92 undergoes through alpha decay and transforms to thorium what is the atomic mass number of the daughter nuclei

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Answer 1

Answer:

234

Explanation:

Alpha decay takes away 2 protons and 2 neutrons. Hence thorium protons = 90, and nucleon number (proton + nuetron) = 234.

Although the atomic mass of thorium is 232, but this is an isotope given in the question.

For calculating the atomic mass we add protons and nuetrons (nucleon number) and electrons. However, as electron mass is almost negligible, that doesn't make a huge difference. Hence, in this case the atomic mass is 234.