Which set of values tells us if the reaction is at equilibrium? A
(Ca2+] = 5.8x10-SM
(CO 321 = 5.8x10-5M
B
k= 47M/s
Ksp = 3.34x107

с
Rate of precipitation = 2.1x108 M/
Rate of dissolution = 2.1x108 M/s

C

Explanation:

A system is at equilibrium when the rates of opposing reactions are equal.

Answer A does not show the rate of reactions, it only shows concentrations of reactants.

Answer B only shows constants, it does not show rates of reactions.

most community's take hundreds of years to become stable