Why does the cell voltage of a mercury cell remain constant during its lifetime?

Question 32:Why does the cell voltage of a mercury cell remain constant during its lifetime?

The correct answer is – The cell voltage of a mercury cell remains constant during its lifetime because the chemical reaction that produces the electrical energy is highly stable and does not change significantly over time. In a mercury cell, the anode is made of zinc, the cathode is made of mercury (II) oxide, and an electrolyte of potassium hydroxide is used. The reaction at the anode releases electrons, which flow through the external circuit to the cathode, where they are used to reduce the mercury (II) oxide to liquid mercury. This reaction is highly stable and does not produce byproducts that can interfere with the electrode surfaces, and therefore the cell voltage remains constant over the lifetime of the cell.