A solution that contains a system at equilibrium is the one in which there is no change in color
Explanation:
If the color of the solution changes slowly it means that the equilibrium shifts towards the right. This happens when we add the reactant and the equilibria move towards the right that is away form the reactant increasing the product formation. But when there is no change in color it means the reaction is constant and there is a state where the concentrations of reactant and product are not changing and are constant.
Hence, the solution in which the color is not changing is at equilibrium.
Aniline has smallest Rf value on silica gel since it is more polarthan the other compounds because aniline is a hydrogen donor and acceptor itmakes the molecule more attracted to the silica gel which is also also polar as<span>‘likes dissolve likes.’</span>