1. is mass conserved when 50 g of sugar undergoes a physical change? use complete sentences to support your answer by explaining how this can be demonstrated. 2. during an investigation a scientist burned 48 g of magnesium strip. after the reaction the total mass of the product formed was found to be 80 g. does the law of conservation of mass hold true in this case? use complete sentences to justify your answer based on numerical calculations.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)