a) If 65.65 g of mercury(II) nitrate and 4.26 g of hydrogen sulfide are mixed in 490.0 g of water to form 54.16g of precipitate, what is the mass of solution after reaction?b)a piece of gold jewelry weighs 9.35g. Its volume is 0.654 cm3. Assume that the metal is an alloy of gold and silver, which have densities of 19.3 g/mL and 10.5 g/mL respectively. Also assume that there is no change in volume when the pure metals are mixed. Calculate the percentage of gold (by mass) in the alloy. The relative amount of gold in an alloy is measured in karats. Pure gold is 24 karats; an alloy of 50% gold is 12 karats. State the proportion of gold in the jewelry in karats.