Physics · Composition and size of nucleus, atomic masses, mass-energy relation, mass defect

The radioactive decay of uranium into thorium is expressed by the equation Where

The radioactive decay of uranium into thorium is expressed by the equation \( 92 U^{238} \rightarrow 90 T h^{234}+X \) Where \( X \) is

  • A. an electron
  • B. a proton
  • C. a deuteron
  • D. an alpha particle

Step-by-step solution

In alpha decay, the nucleus emits an alpha particle (2 protons and 2 neutrons), decreasing atomic number by 2 and mass number by 4. Here, uranium-238 (Z=92, A=238) decays to thorium-234 (Z=90, A=234), so X must be an alpha particle.
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