Why is twice as much hydrogen produced than chlorine in the electrolysis of brine?

I have seen a great many number of diagrams which show the electrolysis of brine in a diaphragm cell, but show twice the volume of hydrogen produced. For example:


[![Brine Electrolysis Diagram 1](https://i.stack.imgur.com/dQ2cK.jpg)](https://i.stack.imgur.com/dQ2cK.jpg)


On the other hand, other diagrams show that the same volume of hydrogen and chlorine is produced. For example:


[![Brine Electrolysis Diagram 2](https://i.stack.imgur.com/BIuNV.png)](https://i.stack.imgur.com/BIuNV.png)


So who's right and why?




It appears, as the others have said that the same number of moles of gas of chlorine and hydrogen is produced.


**Then why are there different levels of solution?**


Since the solution is taken out in the cathode chamber, the level of solution present is lower than the anode chamber where sodium chloride solution is being added in.


[![Electrolysis of Brine Diagram](https://i.stack.imgur.com/fKIZQ.png)](https://i.stack.imgur.com/fKIZQ.png)


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I'm not sure how the first diagram shows a $2:1$ volume ratio. But I am sure about the balanced chemical equations:


$$
\begin{align}
\ce{2 Cl^- &→ Cl2 + 2 e-} \\
\ce{2 H2O + 2 e- &→ H2 + 2 OH-} \\
\hline
\ce{2 H2O + 2 Cl- &→ H2 + Cl2 + 2 OH-} 
\end{align}
$$


Thus equal amounts of both gases are produced, and at the same temperature and pressure that implies equal volumes by the ideal gas law.


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