Is that all? That doesn’t help us give the answers
This problem may easily solved by applying the conservation of mass, which states that the total mass before and after a change is constant because mass can neither be created nor destroyed.
We know that water consists of only hydrogen and water, and that there are no other reactants except hydrogen and oxygen. Thus:
Mass of reactants = Mass of product
mass of hydrogen + mass of oxygen = mass of water
4 + mass of oxygen = 36
mass of oxygen = 32 grams
c) the salt solubility decreases with temperature.
Salts usually dissolve in water at a given temperature. When water cannot dissolve anymore salt at that same temperature, it is known as a saturation point. With most substances the solubility increases with increase in temperature. Same is the case for a salt like potassium nitrate. With increase in temperature the ability of it to dissolve in water increases. And so with decrease in temperature, the solubility decreases.