Consider the full set of reactions required to purify zinc metal. Step 1: ZnCO3 + heat → ZnO + CO2 Step 2: ZnO + C + heat → Zn + CO How do the oxidation numbers of Zn and C change throughout these two reactions? Which compound is the oxidizing agent and which is the reducing agent in each step?

If a reactant was removed, did the new equilibrium system shift to make more reactants or more products?

Which type of fossil does this image depict?

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.