Why are the elements take part in bonding​

Which rate indicates the number of children that would be born per woman if she were to live to the end of her child bearing years

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.

What is the source of continuous heat and energy that we receive from the sun