Har oksygen og hydrogen - hver for seg en krystallisk form?
Hvilke?

Under normale forhold opptrer både oksygen og hydrogen i gassform.
Hydrogen smelter ved 13,99 K og koker ved 20,271 K
Hydrogen kan få metall-karakter under ekstremt trykk. (Som i senter av Jupiter?)
https://en.wikipedia.org/wiki/Hydrogen

Oksygen smelter ved 54,36 K og koker ved 90,188 K.
"The metastable molecule tetraoxygen (O₄) was discovered in 2001,and was assumed to exist in one of the six phases of solid oxygen. It was proven in 2006 that this phase, created by pressurizing O₂ to 20 GPa, is in fact a rhombohedral O₈ cluster. This cluster has the potential to be a much more powerful oxidizer than either O₂ or O₃ and may therefore be used in rocket fuel. A metallic phase was discovered in 1990 when solid oxygen is subjected to a pressure of above 96 GPa and it was shown in 1998 that at very low temperatures, this phase becomes superconducting."
https://en.wikipedia.org/wiki/Oxygen​
Her omtalt krystallisk oksygen under ekstreme forhold...