A uranium nucleus emits an α particle. Assuming charge is conserved, the resulting nucleus must be (a) thorium
(b) plutonium
(c) radium
(d) curium

Video Transcript

This is College Physics Answers with Shaun Dychko. A uranium nucleus emits an alpha particle, which is a helium nucleus that has 2 protons and 2 neutrons and we have to look up the atomic number for uranium in order to understand what nucleus will be created so the atomic number of uranium is 92 and so take away 2 protons used up for the alpha particle— that leaves 90 protons left over— and the element with an atomic number of 90 is thorium so the answer is (a).