please show all steps clearly

6) Patty has a pendant she thinks is made of pure gold. To test this, she measures the mass of the pendant and finds it's 25.0g. The density of gold is 19.3g/ml. What is the volume of the pendant (use appropriate significant figures). 7) Solve & show the correct number of significant figures: (1.8 x 1099X (2402) = Page 1 of chem 301_exam1_review_Sp20.docx 8) A pollution scientist wanted to see where the pollution in a river was coming from. He collected the following facts: the river ran downstream. At the lowest point there was lead, mercury, and detergent in the river. At a town upstream from the river there was mercury but no other pollutants in the river. At a factory upstream from the town, there were no pollutants in the river. What hypothesis can the scientist draw regarding the source(s) of pollution in the river?