Note: pm is ”picometer” or 1 x 10-12 m.

calculate the answer in units of g/cm3.

calculate the average density of a single

atom by assuming that it is a uniform sphere

of radius 135.9 pm and its mass is 5.71 ×

10^−22 g. the volume of a sphere is 4

3

π r3

.

answer in units of g/cm3

.

What can be added to the examples section of each circle? endothermic: ice melting into water, and a heat pack becoming warm exothermic: a glow stick glowing, and fireworks exploding endothermic: ice melting into water, and an instant ice pack turning cold exothermic: fireworks exploding, and gasoline burning endothermic: a glow stick glowing, and a heat pack becoming warm exothermic: an instant ice pack turning cold, and ice melting into water endothermic: gasoline burning, and an instant ice pack turning cold exothermic: ice melting into water, and an instant ice pack turning cold

Which electron configuration represents the electrons in an atom of sodium in the ground state at stp

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.