Question

Why we take ratio of hydrogen and oxygen 2:1 in electrolysis of water?

Answer 1

The formula of water is H20, this means that in every molecule of water:

There are 2 atoms of hydrogen and 1 atom of oxygen

So if 1 molecule of water is electrolized then 2 atoms of H and 1 atom of O

*Although it does not happen this way the gases Hydrogen and Oxygen do not exist in atomic state but in moecular state.

So, 2 molecules of water have the formula 2.H20,

In this, there are 4 atoms of Hydrogen and 2 atoms of Oxygen.

Atlast, there will be 2 molecules of Hydrogen released at the cathode(negative electrode) and 1 molecule of Oxygen at the anode(positive electrode)