A chemical equation is shown: Na + H2O → NaOH + H2 According to the law of conservation of mass, how many atoms of hydrogen exist in the products of this reaction? (3 points) 2 3 4 6

Which of the following are sources of revenue for media companies? a. direct sales to producers b. advertising and subscriptions c. online purchase d. capital investments

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.

•hydration •dissociation •dissolving which one goes to which