The electrolyte of a nickel-cadmium battery is the lowest when the battery is ______.

The electrolyte of a nickel-cadmium battery is the lowest when the battery is ______.

• A. In a discharged condition
• B. Fully charged
• C. Resting
• D. Overcharged

Answer: (A)

The electrolyte level in a nickel-cadmium cell reflects the water content of the alkaline solution (typically KOH in water) in the cell. When the battery is discharged, the reactions at both electrodes consume water. The overall discharge reaction is NiO(OH) + Cd + H2O → Ni(OH)2 + Cd(OH)2, which uses up that water from the electrolyte. As a result, the liquid level drops during discharge. When you charge the battery, the reactions tend to produce water, which would raise the electrolyte level (though gas evolution during charging can complicate this). So the electrolyte is lowest in the discharged condition.

The electrolyte level in a nickel-cadmium cell reflects the water content of the alkaline solution (typically KOH in water) in the cell. When the battery is discharged, the reactions at both electrodes consume water. The overall discharge reaction is NiO(OH) + Cd + H2O → Ni(OH)2 + Cd(OH)2, which uses up that water from the electrolyte. As a result, the liquid level drops during discharge. When you charge the battery, the reactions tend to produce water, which would raise the electrolyte level (though gas evolution during charging can complicate this). So the electrolyte is lowest in the discharged condition.