20 ! plz ; 3; two pieces of silk have an electric charge after being rubbed on a peice of amber. what will happen when the two silk peices are bought close together. a) they will transfer their electrons from one to the other b) they will not affect one another. c) they will attract one another. d) they will repel one another.

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.