Physics 0625 · IGCSE · Radioactivity

Radioactivity — practice question

A uranium nucleus $^{{238}}_{{92}}\text{U}$ undergoes decay to produce thorium by releasing an $\alpha$-particle. Thorium then decays into protactinium by releasing a $\beta$-particle. Which row shows the atomic number and mass number for this isotope of protactinium?

  • Aatomic number 89, mass number 234
  • Batomic number 90, mass number 235
  • Catomic number 91, mass number 234
  • Datomic number 95, mass number 235

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