The answer to the king and 2 sons riddle?

In a certain country, there lived a king who had two sons. One day the king summoned his two sons and said to them, " I have hidden the golden ball inside one of the two bags. The one who can guess inside which bag the ball is, will inherit my kingdom." On examining both the bags, the sons found both of them to be of the same size, weight and shape. After some time, one son gave the correct answer. How did he know?

Answer: The ball was inside the bag with holes because the other bag was perfectly sealed while the other bag had air coming inside through the holes.