Which of the following statements correctly describes any chemical reaction that has reached equilibrium?
a. the concentration of products and reactants are equal.
b. the reaction is now irreversible.
c. both forward and reverse reactions have halted.
d. the rates of the forward and reverse reactions are equal.

Option (d).

Explanation:

Equilibrium may be defined as the state of  the equality on both the sides of the reaction. Different types of equilibrium are physical equilibrium, chemical equilibrium and dynamic equilibrium.

Chemical equilibrium may be defined as the equilibrium in which the reactants and products concentration remains constant with time. The rate of the backward reaction is equal to the rate of forward reaction.

Thus, the correct answer is option (d).

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