Which of the following is true for a system whose equilibrium constant is much greater than one?
a) the reaction mixture contains mostly products at equilibrium.
b) the reaction mixture contains mostly reactants at equilibrium.
c) the rate of reaction is very fast.
d) the moles of reactants and products are relatively similar at equilibrium.
e) both a and c.

A) The reaction mixture contains mostly products at equilibrium  

Explanation:

For the general reaction

Reactants ⇌ Products

The equilibrium constant is

Thus, if K is large, the concentration of products is greater than that of reactants.

The reaction mixture will contain mostly products at equilibrium.

C) and E) are wrong. The equilibrium constant gives us information only on the position of equilibrium, not on how fast it is achieved.