Consider the following statements:

(A) Rate of a process is directly proportional to its free energy change

(B) The order of an elementary reaction step can be determined by examining the stoichiometry

(C) The first-order reaction describes an exponential time course.

Of the statements:

A and C are correct

(A) Rate of a process is directly proportional to its free energy change.
This statement is incorrect. The rate of a process is not directly proportional to its free energy change. The rate of a reaction is determined by factors such as the activation energy, temperature, and concentration of the reactants, but it is not directly related to the free energy change.

(B) The order of an elementary reaction step can be determined by examining the stoichiometry.
This statement is incorrect. The stoichiometry of an elementary reaction step does not directly determine the order of the reaction. The order of a reaction is determined experimentally and is not solely based on the stoichiometry of the reaction equation.

(C) The first-order reaction describes an exponential time course.
This statement is correct. A first-order reaction follows an exponential time course. The concentration of the reactant decreases exponentially with time, and the rate of the reaction is proportional to the concentration of the reactant raised to the power of 1 (i.e., first order).
The correct answer is (2) A and C are correct.