Question

1000 mL 1 M $CuS{O}_4\left(aq\right)$ is electrolysed by 9.65 amp current for 100 sec using $Pt-$electrode. Which is incorrect statement?

• A. Blue colour intensity decreases during electrolysis
• B. Blue colour intensity remains constant if $Cu-$electrode used
• C. At anode $O_2$ gas liberated during electrolysis
• D. $pH$ of solution is 8 after electrolysis

Answer 1

Answer: (D)

${CuSO}_4\rightleftharpoons {Cu}^{2+}+{SO}_4^{2-}$ is formed from strong acid $H_2{SO}_4$ and weak base ${Cu\left(OH\right)}_2$. Hence, the ${CuSO}_4$ is acidic in nature and it's $pH$ is thus less than $7$ always.

$\therefore$ The incorrect statement is $pH$ of solution after electrolysis is $8$.