Yes, but not for very long. Oxygen is needed to support human or animal life.
From what I know about chemical compunds, there is too much H (Hydrogen) in water for land animals to breathe as there is none in air, or close to it. Also, it doesn't include Argon or Nitrogen.For their counterpart, Water animals can not breathe air(Except for dolphins and lung fish) because they do not reach a sufficient amount of Hydrogen. That's my guess anyway.
Oxygen
Hydrogen gas is not toxic. Of course, if you were to breathe pure hydrogen you would soon suffer from lack of oxygen.
No.
We eat them or breathe the oxygen they produce.
they breathe in the same way as daytime animals
Animals breathe a mix of gases including;NitrogenOxygenCarbon dioxideWaterArgon
The air - what people and animals breathe out etc
They breathe air, which contains oxygen. They do not breathe hydrogen, as it is a bad idea to mix hydrogen and oxygen unless you intend to create anexplosion.
Plants breathe in carbon dioxide and breathe out oxygen; animals breathe in oxygen & breathe out carbon dioxide.
Not much......
No. The sun does not breathe as it is not alive. It is powered by the fusion of hydrogen at its core.