Which is an example of a heterogeneous mixture?
a coffee
b soil
c gelatin
d air

Which describes interactions between substances and stomata during photosynthesis? check all that apply. oxygen enters stomata. oxygen is released through stomata. carbon dioxide enters stomata. carbon dioxide is released through stomata. hydrogen enters stomata. hydrogen is released through stomata.

How do forces between particles in gases compare to forces in the other states of matter? o a. the forces in gases are stronger than forces in solids but weaker than forces in liquids. o b. the forces in gases are weaker than forces in solids but stronger than forces in liquids. o c. the forces in gases are weaker than forces in solids and liquids. o d. the forces in gases are stronger than forces in solids and liquids. submit

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)