Question 6A249

The formation of hydrogen gas bubbles around the positive electrode (cathode) of a primary cell is known as **polarization**. In many primary cells, particularly older designs like zinc-carbon cells, the chemical reactions at the electrodes produce hydrogen gas at the positive electrode. These gas bubbles accumulate on the electrode surface, acting as an insulating layer. This accumulation effectively increases the cell's internal resistance, which in turn reduces the available voltage and current output. This decrease in efficiency and power is a significant drawback caused by polarization. Depolarization (A) is the *process* of preventing or reversing polarization, often by adding a chemical like manganese dioxide (C) that reacts with the hydrogen gas to remove it from the electrode surface. Manganese dioxide (C) itself is a depolarizing agent, not the phenomenon of gas formation.