Is temperature-induced change in the volume of balloons dependent on gas? Which balloon will have higher relative change in volume, helium balloon immersed in liquid nitrogen or air balloon immersed in liquid nitrogen? Since volume is directly proportional to temperature does the gas in the balloon matter?
 A: While studying the behavior of a gas filled balloon on cooling down, one needs to understand how the gases behave while being cooled. A helium filled balloon immersed in liquid nitrogen would just undergo shrinkage due to contraction of helium gas. On the other hand, a balloon filled with air will behave differently. Air roughly contains 77% nitrogen, 22% oxygen and 1% argon, carbon dioxide, etc. Any stable balloon in atmospheric air must have at least 1 atmosphere inside it, otherwise it will shrink (In reality the pressure inside is actually more than outside so as to overcome the elastic force of the balloon material). If this air filled balloon is immersed in liquid nitrogen, the nitrogen part of air inside will reduce in volume while the oxygen part will simply turn to liquid (argon will shrink, CO2 will turn solid!). The volume loss due to phase change is much more than simple contraction of gas on cooling. As a result, the air balloon will actually reduce much more in size as compared to the helium filled balloon. 
