The number of correct statement/s involving equilibria in physical processes from the following is _______.
(A) Equilibrium is possible only in a closed system at a given temperature.
(B) Both the opposing processes occur at the same rate.
(C) When equilibrium is attained at a given temperature, the value of all its parameters became equal
(D) For dissolution of solids in liquids, the solubility is constant at a given temperature.

Let us verify each statement about equilibria in physical processes:

(A) Equilibrium is possible only in a closed system at a given temperature. Correct - a closed system is needed to prevent exchange of matter.

(B) Both the opposing processes occur at the same rate. Correct - this is the definition of dynamic equilibrium.

(C) When equilibrium is attained, the value of all its parameters became equal. Incorrect - the parameters (like concentration, pressure) become constant, not necessarily equal.

(D) For dissolution of solids in liquids, the solubility is constant at a given temperature. Correct - at equilibrium, the solubility (amount dissolved) is fixed at a given temperature.

The number of correct statements is A, B, D = 3.