Which of the following expressions best represents a second order rate law?
a. r =k
b. r =k[x]
c. r =k[x][y]
d. r = k[x]x[y]y

I think the correct answer would be C. The expression that would best represent a second order rate law would be r =k[X][Y]. Reaction with this rate law are those that depend on the concentration of two first order reactants or a second order reactant.

The answer is 323 g.