A mountaineer shouts for help Half a second later (0.5 she hears the echo How far away is the rock face which is reflecting her voice (take the speed of sound to be 330 m/s

Which terms are used to identify pure substances

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.

Na chemical reaction, activation energy increases the of the reactants. this outcome causes the particles to collide, which results in the of new products.