En una solución de 0.20 L de Oxígeno y 0.80 L de Nitrógeno

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other

Molarity is moles of solute over liters of solution. idk if that is what you are talking about, but you can convert moles of solute to grams of solute using dimensional analyzes by using molar mass found on the periodic table.

Rate law for this reaction israte of the reaction = k[a]²[b].second order in a  means concentration of a in power of two, and  first order in b means concentration of b in power of one.

Ibelieve the answer is weathering,hope my answer has you : )