Most of the radiation emitted by hydrogen flames is in the ultraviolet spectrum, which is invisible to humans. This usually makes the flames colorless, but they sometimes have a very faint blue or purple tint.
Hydrogen burns with a pale blue flame.
All stars 'burn' hydrogen
Can't tell, 'cause water doesn't burn. Water is totally oxidized hydrogen. It is essentially hydrogen "ash". Just as you cannot reignite the ashes from a fire you cannot re-burn water after hydrogen is burned with oxygen to water.
No hydrogen will not burn in the absence of air unless another oxidizer is present.
helium does not burn, hydrogen will burn in air
You get and orange - yellow colour.
Hydrogen gas is highly flammable; you can make it burn with the slightest spark.
Yes. When you burn hydrogen the product is water. If you pass an electric current through that water you can split it back into hydrogen and oxygen.
You don't. Sea water is the combustion byproduct of hydrogen. That is, water is water you get when you burn hydrogen.
When you burn hydrogen and oxygen, the molecules combine to form water (H2O).
Hydrogen gas has no taste, colour or smell.
Burn hydrogen