When the common ion effect is in action, the equilibrium of a system will shift to: Select the correct answer below: a. decrease the amount of the common ion in the system
b. increase the amount of the common ion in the system
c. depends on the ion
d. The system will not shift at all.

a. decrease the amount of the common ion in the system

Explanation:

The correct option is - a. decrease the amount of the common ion in the system

Reason -

Adding a common ion decreases solubility, as the reaction shifts toward the left to relieve the stress of the excess product.

Adding a common ion to a dissociation reaction causes the equilibrium to shift left, toward the reactants, causing precipitation.