How many hydrogen molecules are needed to produce two H2O molecules

There are 2 Hydrogen molecules in H2O

Explanation:

if you look at the symbol for Hydrogen (H) you see that there is a number beside it, to the right. That number shows how many molecules there are of that element.

(Sidenote: If there is no number there is only one molecule)

Hope this helped :)

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.