(1) This generator is of solid-liquid normal temperature type, which is suitable for the reaction between solid and liquid at normal temperature to generate gas. In the laboratory, this generator can be used to generate oxygen from hydrogen peroxide and zinc particles and hydrogen from dilute sulfuric acid.

(2) Hydrogen peroxide decomposes to generate water and oxygen, and the chemical equation is: 2H2O2? MnO2？ . ? 2H2O+O2↑ =, zinc particles react with dilute sulfuric acid to generate zinc sulfate and hydrogen,

Zn+H2SO4═ZnSO4+H2↑

(3) Before preparing the required gas, it was found that the device was airtight. However, after adding the solid, covering the rubber stopper and dropping the reaction solution, there is no bubble in the test tube, indicating that the device is leaking and the stopper is not tightly plugged.

So the answer is:

( 1)O2； H2 (If you fill in "CO2" or "NO2" or "SO2" or "H2S", you will also get a score; If you fill in less, you won't get points)

(2)2H2O2？ MnO2？ . ? 2H2O+O2↑,Zn+H2SO4═ZnSO4+H2↑

(or fill in "CaCO3+2HCl═CaCl2+CO2↑+H2O")

(3) Tighten the rubber plug.