What is an electron dot structure? (Lewis dot structure) Group of answer choices

A filled noble gas in brackets plus the remaining electron configuration expressed by filled orbitals

An element symbol surrounded by dots representing its valence electrons

An element symbol surrounded by its innermost electrons

An element symbol with a positive charge

What happens to energy in an open system?

Evaluate this exponential expression,8. (2 + 3)2 – 42

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.