|Graphite and heavy water are ____ that slow down neutrons.
|Nuclei ____ during nuclear fusion reactions.
|Radioactive carbon-14 is used to study organic reaction ____.
|The ____ of two hydrogen atoms produces a helium atom.
|All carbon isotopes (e.g. C-12 and C-14) have ____ protons.
|U-233, U-235, and Pu-239 are used as ____ in fission reactors.
|Carbon-14 is used to date organic ____ samples.
|A molecule of ____ contains one or two atoms of deuterium.