ANS:C - decrease in equilibrium solubility.

Absorption accompanied by heat evolution results in: Decrease in equilibrium solubility. When heat is evolved during absorption, it indicates an exothermic process. In an exothermic absorption process, the absorption of the solute into the solvent is accompanied by the release of heat. This increase in temperature can cause a decrease in the solubility of the solute in the solvent. According to Le Chatelier's principle, when a system at equilibrium is subjected to a change in temperature, the system responds in a way to counteract that change. In the case of an exothermic absorption process, where heat is evolved, the equilibrium shifts in a direction to consume the excess heat. This shift results in a decrease in the solubility of the solute in the solvent to offset the increase in temperature, thereby maintaining the system at equilibrium. Therefore, absorption accompanied by heat evolution typically results in a decrease in equilibrium solubility.