A bottle of coke was taken out of refrigerator. It was then kept in a sensitive weighing balance.Its cap was opened. The initial weight was found to be 2.403 kg. After a while its weight increased to 2.423 kg. Then again it started decreasing. I repeated this experiment for many times. And the result was the same the weight first increased and then started decreasing. But I think that the weight must plainly start to decrease because the coke molecules will evaporate. Please explain this fairly contradictory result to me.