1. a substance that is changed during a chemical reaction is called
2. matter cannot be created or__
in a chemical reaction.
3.
takes place during the formation of rust.
4. increasing surface area of a reactant
- the speed of the reaction.

Nickel crystallizes in the face-centered cubic (fcc) lattice. the density of the metal is 8902 kg/m3. calculate the radius of a nickel atom.

What are the two largest greenhouse gases

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.