Answer: Theoretical prediction; metallic H may exist in gas giant planet cores (Jupiter).
- A Theoretical prediction; metallic H may exist in gas giant planet cores (Jupiter)
- B Routine laboratory observation at ordinary atmospheric pressure under usual circumstances
- C A stable solid state generally by cooling hydrogen to -200°C according to most researchers
- D Mainly ever observed as an ordinary cryogenic liquid in the majority of cases studied
Correct answer: A. Theoretical prediction; metallic H may exist in gas giant planet cores (Jupiter)
Explanation: Metallic hydrogen is predicted to form above 400 GPa; experimental evidence is disputed. It likely exists in Jupiter's core.
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.