Question

what is the mass of oxygen and hydrogen in 1 kilogram of water

Answer 1

Theoretically, water could be made from a molecule of Oxygen and 2 molecules of Hydrogen. To make 1 Kg of water(MW 18 g), you would need 1/9 Kg Hydrogen (MW 2 g) and 8/9 Kg Oxygen (MW 32 g).But you cannot just "make" water by mixing these two. You need energy and since hydrogen is flammable and oxygen supports combustion, this reaction is dangerous, rather deadly. There shall be an explosion. You will have water though.There are other methods of "making" water, like from thin air or as byproduct of various industrial processes but there has been no considerably successful method, hence the problem of water scarcity is a major one.