Hydrogen is a type of gas. Hydrogen is part of water, which is two parts hydrogyn and one part oxygen.
Hydrogen has a mean weight of 1.00794 u and was discovered in 1766
it is the number of mole in hydrogen per cubic decimeyer
I guess you mean "hydrogen". Mars doesn't have any significant hydrogen.
There is one electron per hydrogen atom, and two atoms per molecule of hydrogen. So if you mean hydrogen gas, there are two electrons.
Depends on what you mean by "get clean"?
Hydrogen peroxide
Assuming that you mean Hydrogen, its formula is H2, hydrogen is diatomic molecule
Hydrogen peroxide
hydrogen
Hydrogen Peroxide itself is as colorless as water. Hydrogen peroxide solution is a bit ambiguous, and could vary with what you mean by "solution".
If you mean hydrogen in elemental form, it's darn near zero.
In the term "pH," the "H" stands for hydrogen. pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or alkalinity.