(2008? Zhanjiang) As shown in the figure, A is a substance composed of two elements, and B is the product of decomposition of potassium permanganate by heating. The balloon is sleeved on the mouth of the test tube and protected. The products of thermal decomposition of potassium permanganate are potassium permanganate, manganese dioxide and oxygen. B is the product of thermal decomposition of potassium permanganate, which may be potassium permanganate or manganese dioxide. B all pour into A in the test tube. A is composed of two elements, which have common gas generation, so it can be inferred that A is hydrogen peroxide, B is manganese dioxide, and the gas is oxygen.

According to the law of conservation of mass, the total mass of substances before and after the reaction remains unchanged, and the mass of the whole device (including drugs) is100g;

According to the fact that oxygen is colorless, odorless, insoluble in water and slightly higher in density than air, it can be seen that the balloon sinks in the air;

The chemical equation of the reaction is: 2H2O2? MnO2？ . ? 2H2O+O2↑ write, so the answer is:100g; ; Sink; 2H2O2？ MnO2？ . ? 2H2O+O2↑。