Question

During electrolysis of aqueous solution of a salt, the pH in the space near one of the electrodes is increased.Which of the following salt solution was electrolysed....?
1.KCl
2.CuCl2 
3.Cu(NO3)2 
4.CuSO4

Answer 1

The answer is option 1 that is KCl . As here the K+ ion that is cation has lower electrode potential than H. Thus hydrogen is liberated at cathode and accumulate at one electrode and results in increase in pH.

Answer 2

"During electrolysis of aqueous solution of a salt, the pH in the space near one of the electrodes is increased. Here KCl has lower electrode potential and the in KCl solution the reaction at the electrodes is given below,

                             $2H^+ + 2e^- \rightarrow H_2$

                             $2Cl^- \rightarrow Cl_2 + 2e^-$

The $H_2$ liberated at the cathode, accumulate at one electrode and thereby the pH increases or in other words, the concentration of $H^+ ions$decrease because the concentration of hydroxide ions increases thereby increasing the pH."