Answer: 3 (protium, deuterium, tritium).
- A 3 (protium, deuterium, tritium)
- B 2, counting only protium and deuterium
- C 4, including a hypothetical quadrium isotope
- D 1, since hydrogen has no other known isotopes
Correct answer: A. 3 (protium, deuterium, tritium)
Explanation: Hydrogen has three isotopes: protium (1H, no neutrons), deuterium (2H, 1 neutron), and tritium (3H, 2 neutrons, radioactive).
Each water molecule's O-H bonds (covalent, solid) can hydrogen-bond (dashed) to neighbouring molecules, forming an extended network responsible for water's unusually high boiling point and density anomaly.
Concept context
The simplest and most abundant element in the universe. Study its unique position in the periodic table, isotopes (protium, deuterium, tritium), properties of water and hydrogen peroxide, and industrial uses.