| # | Concept | Culture | Statement | Freq. |
|---|---|---|---|---|
| 1 | protium | chemistry | Protium is the most common isotope of hydrogen with one proton and no neutrons, widely studied in chemistry and physics. | 5 |
| 2 | protium | physics | Protium is the predominant isotope of hydrogen, consisting of one proton and no neutrons, and is studied in chemistry and physics. | 3 |