On my last test there was a question saying “NH4Cl is dissolved into water. The temperature change measured decreases over time. Is it exothermic, endothermic or is there not enough information?” I said there was not enough information because there is no information on an increasing or decreasing temperature just a decreasing rate of change. The answer key said it was endothermic. Am I correct, and if so how do I explain it to my professor?