If you burn 46.6 g of hydrogen and produce 416 g of water, how much oxygen reacted

369.4 g.

Explanation:

The chemical reaction of reacting hydrogen with oxygen to produce water is:

H₂ + 1/2 O₂ → H₂O.

From the law of conservation of mass states that the mass does not destroyed or created from nothing but it can converted from from to another one. The mass of the reactants = the mass of the products

∴ The mass of hydrogen + the mass of oxygen = the mass of water.

∴ The mass of oxygen = the mass of water - the mass of hydrogen = (416.0 g) - (46.6 g) = 369.4 g.