Which of the following substances is an electrolyte?

On electrolysis of dilute sulphuric acid using Platinum $(Pt)$ electrodes,the product obtained at the anode will be:

Which of the following electrolytes can be used to obtain $H_2S_2O_8$ by the process of electrolysis?

Give the electrolytic reaction of a concentrated aqueous $NaCl$ solution using inert electrodes.

When acidulated water ($dil. H_{2}SO_{4}$ solution) is electrolysed,will the $pH$ of the solution be affected? Justify your answer.

For the extraction of sodium from $NaCl$,an electrolytic mixture of $NaCl + Na_3AlF_6 + CaCl_2$ is used. During the extraction process,only sodium is deposited at the cathode,while $K$ and $Ca$ are not,because: