Are you referring to the fact that water is a compound while hydrogen is an element? If I'm wrong just comment and clarify and I can edit it, I don't even know what kind of unit you're in. :)
Answer:
upthrust
Explanation:
i think it does not sink in water because of the force pulling it upwards
Answer:
F = 1300 N
Explanation:
F = mv²/R = 0.4(100²)/3 = 1333.3333...