Consider a hypothetical reaction between a, b, and c that is first order in a, zero order in b, and second order in
c.

Let d be the product of the reaction between these hypothetical reactants. The reaction would be,
                                a + b + c --> d
Since it is first order in a, zero order in b, and second order in c, the rate of reaction equation should be expressed such as that below.
                                 r[d] = [a][c]^2