Need help with 4 pls

Write a net ionic equation to show that hydrofluoric acid, behaves as an acid in water.

Calculate the change in entropy if br2(l) is converted to br2(g). s° for br2(l) = 152.2 j/(mol•k) s° for br2(g) = 245.5 j/(mol•k) s° for br(g) = 175.0 j/(mol•k)

If 16.00g of hydrogen gas reacts with 126.73g of oxygen, how many grams of water are yielded? (both reactants are completely consumed in the reaction.)