which of the following statements is/are correct? i. A molecule is nonpolar if it contains only nonpolar bonds ii. A polar molecule is one in which there is an asymmetrical distribution of charge. iii. If the central atom in a molecule has no lone pairs and all the atoms bonded to it are identical, the molecule is nonpolar.

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.