Question

why is amount of gas collected in one of the test tube double of the amount collected in other on electrolysis of water? name the gas

Answer 1

Electrolysis of water causes the molecules to break apart resulting in individual molecules of the constituent gases H2 and O2. Since hydrogen is naturally available in double the amount as oxygen, the gas which is double is hydrogen.

Answer 2

Hey there!

----------

Q. Why is the amount of gas collected in one of the test tubes double the amount of gas collected in the other? Name this gas.

Answer : If we study the composition of water, i.e. the chemical formula $H_{2}O$, we observe that the molar ratio of hydrogen and oxygen is 2 : 1. When water is electrically decomposed, the constituent gases hydrogen and oxygen are produced in the same molar ratio, i.e. the amount (volume) of hydrogen is double than that of oxygen. So, this gas is hydrogen.