8. A party-supply store sells a helium-gas
cylinder with a volume of 1.55 x 10-2 m². If
the cylinder provides 1.81 m3 of helium for
balloon inflation (at 0 °C and 1 atmosphere),
what must be the pressure inside the
cylinder? eldsinsvinebnegabais
oldeltsvinebaogob
mollaoup oldsteel 3

In a popular classroom demonstration, solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide. part a write a balanced chemical equation for this reaction. express your answer as a chemical equation. identify all of the phases in your answer.

Which common material is an example of a polymer? (25 pts) a. steel b. plastic c. petroleum d. rubbing alcohol

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.