A. the litmus turns blue but no gas is evolved
B. the litmus turns blue and oxygen is evolved
C. the litmus turns blue and hydrogen is evolved
D. the litmus turns red and oxygen is evolved
Correct Answer:
Option D – the litmus turns red and oxygen is evolved
Explanation
During the electrolysis of copper using platinum electrode, Cu and H migrate to the cathode while, SO4 and OH migrate to the anode.CU is then discharged preferentially at the cathode, acquiring two electrons and is deposited as metallic copper, while OH is discharged preferentially at the anode and deposited as gaseous oxygen, then the SO4 and H still in the solution react, thereby making d solution acidic and then changing the litmus paper red which is the test for acids.
