When an atom of Uranium-238 undergoes alpha decay, it becomes ____.
A)U-234
B)U-236
C)Th-234
D)Th-236
E)Th-238

Question

Quizplus · Accepted Answer

When Uranium-238 undergoes alpha decay, it emits an alpha particle (which is a Helium nucleus), causing the atomic number to decrease by two and the mass number to decrease by four. Thus, the resulting nucleus has an atomic number of 90 and a mass number of 234, which is the isotope Thorium-234.

When an Atom of Uranium-238 Undergoes Alpha Decay, It Becomes