Answer: The chemical reaction involved in the electrolysis of water is From the above reaction it is clear that the amount of hydrogen gas and the oxygen gas formed are always in the ratio of 2:1. Therefore thevolume of gas collected in the first test tube is double the volume of the gas collected in second test tube.

The amount of gas collected in one of the test tubes during the electrolysis of water is equal to the amount collected in the other test tube because of the law of conservation of mass. This law states that matter cannot be created or destroyed, only transformed from one form to another.

The gas collected during the electrolysis of water is hydrogen gas. When water is electrolyzed, it breaks down into its component parts - hydrogen and oxygen gas. These gases are collected in separate test tubes at the anode and cathode respectively.


During the electrolysis of water, the following reaction takes place at the anode and cathode:
- At the anode: 2H2O → O2 + 4H+ + 4e-
- At the cathode: 4H+ + 4e- → 2H2


Since the reaction at the cathode produces twice as much hydrogen gas as the reaction at the anode produces oxygen gas, the amount of hydrogen gas collected in one test tube is equal to the amount of hydrogen gas collected in the other test tube.

This is because the number of hydrogen atoms produced during the reaction at the cathode is equal to the number of hydrogen atoms consumed during the reaction at the anode. Therefore, the total mass of hydrogen gas produced is the same in both test tubes.


In conclusion, the amount of gas collected in one test tube during the electrolysis of water is equal to the amount of gas collected in the other test tube because of the law of conservation of mass. The gas collected is hydrogen gas, which is produced in equal amounts at both the anode and cathode.