I have multiple questions. I need them ASAP pls. 1)-Air is a mixture because its composition (or proportions) can change. Why is this statement right?
2)-Air is a mixture because it is odorless at low temperatures. Why is this statement wrong?
3)-Air is a mixture because it is colorless when unpolluted. Why is this statement wrong?

Using this reversible reaction, answer the questions below: n2o4 2no2 (colorless) (reddish-brown) -as the temperature increased, what happened to the n2o4 concentration? -was the formation of reactants or products favored by the addition of heat? -which reaction is exothermic? right to left or left to right? -if the change of enthalpy of this reaction when proceeding left to right is 14 kcal, which chemical equation is correct? n2o4 2no2 + 14 kcal n2o4 2no2, hr = +14 kcal n2o4 + 14 kcal 2no2 n2o4 2no2, hr = -14 kcal