200
Imagine a balloon filled with helium on a cold winter day. While you are in the shop, the balloon is normal. As you step outside the balloon begins to shrivel up. This happens because of the temp. of the helium in the balloon deceases and becomes less dense, because the helium particles lose energy and become more concentrated, decreasing the volume. But when you put the balloon in a warm area, it goes back to its original size.
Charles's Law