Which of there statments are not true about chemical rates?
a. the reaction rates are always constant
b. the reaction rates decrease
c. the reaction rates can increase
d. the reaction rates change

The corresponding statement that is true of chemical rates would be A. The reaction rates are always constant. Depending on the chemical reaction and the amount of energy needed for reacting molecules to proceed forward and or reverse, if the reaction is reversible, the change in the substances within however much time needed will change.

Reaction Rate = change in reactant to product/time for reaction.