| Water, heavy water, air, and molten sodium are used as ____. |
control rods |
| Radioactive carbon-14 is used to study organic reaction ____. |
coolants |
| Boron and cadmium are used in ____ to absorb neutrons. |
fuels |
| Unlike electrons, protons and neutrons are ____. |
isotopes |
| Alpha particles are helium ____ formed by radioactive decay. |
mechanisms |
| U-233, U-235, and Pu-239 are used as ____ in fission reactors. |
moderators |
| The ____ of an element have different numbers of neutrons. |
nuclei |
| Graphite and heavy water are ____ that slow down neutrons. |
nucleons |
