What is produced by the dissociation of an electrolyte in an aqueous solution?

Which of the following chemical reactions occurs at the anode during the electrolysis of a highly concentrated $H_2SO_4$ solution?

$KOOC-CH_2-CH_2-COOK \xrightarrow{\text{electrolysis}} (A) (\text{major})$. Product $(A)$ is:

In the industrial production of which of the following,molecular hydrogen is obtained as a byproduct?

Predict the products of electrolysis in each of the following:
$(i)$ An aqueous solution of $AgNO_3$ with silver electrodes.
$(ii)$ An aqueous solution of $AgNO_3$ with platinum electrodes.
$(iii)$ $A$ dilute solution of $H_2SO_4$ with platinum electrodes.
$(iv)$ An aqueous solution of $CuCl_2$ with platinum electrodes.

The product obtained at the anode when $50 \%$ $H_2SO_4$ aqueous solution is electrolysed using platinum electrodes is: