A reaction mixture has reached equilibrium at constant temperature. Which of the following is necessarily true?

A $Q = 1$ for every reaction at equilibrium
BThe concentrations of reactants and products are equal
C $K$ becomes zero because no net change occurs
D $Q = K$ and the forward and reverse rates are equal

Answer: D

At equilibrium the net rate of change is zero because forward and reverse rates are equal, and the reaction quotient has reached the equilibrium constant,

Q = K

K

is generally not 1, and concentrations of reactants and products are generally not equal.

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