Answer:
See the answer below
Explanation:
The percentage by mass of a substance in a mixture is the ratio of the mass of the substance and the mass of the entire mixture.
Hence, when concentrated HNO3 is said to be 69% by mass of nitric acid, it means that the solution of the acid has 69% HNO3 and 31% water in terms of mass. More specifically, 100 g of the solution of the acid would contain 69 g of HNO3 and 31 g of water respectively,
