The correct answer is: D. higher internal resistance.
A nickel-iron cell is a type of secondary cell, also known as a rechargeable battery. It is a type of alkaline battery that uses nickel oxide hydroxide and iron as its active materials. Nickel-iron cells are known for their long life, high capacity, and resistance to deep discharge. However, they also have a higher internal resistance than lead-acid cells, which means that they are less efficient at converting chemical energy into electrical energy.
The internal resistance of a battery is the opposition to the flow of current within the battery. It is caused by the resistance of the electrolyte, the electrodes, and the separator. The higher the internal resistance, the lower the efficiency of the battery.
Lead-acid cells have a lower internal resistance than nickel-iron cells because they use a different type of electrolyte. Lead-acid cells use sulfuric acid as their electrolyte, while nickel-iron cells use potassium hydroxide. Sulfuric acid is a better conductor of electricity than potassium hydroxide, which is why lead-acid cells have a lower internal resistance.
The higher internal resistance of nickel-iron cells means that they are less efficient at converting chemical energy into electrical energy. This is why nickel-iron cells are not as commonly used as lead-acid cells in applications where efficiency is important, such as in cars and power tools.