A. polarization.
B. back e.m.f.
C. electrolysis.
D. local action.
Correct Answer:
Option A – polarization
Explanation
Polarization: The hydrogen bubbles which are clinging over the surface of copper electrode anode becomes a thin film of hydrogen over the copper electrode.
This hydrogen film increases the internal resistance and reduces the emf of the cell and hence the cell soon becomes inactive. This effect is known as polarization