Which of the following is an example of a primary cell?

1. Analyze the question You are asked to identify a primary cell from the options.

2. Explain the concept

• Primary cell: An electrochemical cell that is not rechargeable. Its chemical reaction is irreversible, so once the reactants are used up, the cell is thrown away. Examples: Leclanché (dry) cell, alkaline battery (zinc-manganese dioxide), mercury cell, and the button cells in watches.
• Secondary cell: A rechargeable cell. Its reactions can be reversed by passing current through it in the opposite direction. Examples: lead-acid accumulator, nickel-cadmium (Ni-Cd), nickel-metal hydride, lithium-ion.

3. Solution: check each option

• A. Alkaline battery: Zn/MnO₂ with KOH electrolyte. It is designed for single use, so it is primary. ✔
• B. Nickel-cadmium battery: Rechargeable, so it is secondary. ✘
• C. Lead-acid battery: The car battery, rechargeable, so it is secondary. ✘
• D. Lithium-ion battery: Used in phones and laptops, rechargeable, so it is secondary. ✘

(Note: some non-rechargeable lithium cells exist, such as lithium metal coin cells, but "lithium-ion" specifically refers to the rechargeable type.)

4. Answer The correct option is A. Alkaline battery.

5. Exam tip Remember: Primary = Poured away, Secondary = Supplied again (recharged). If you see a car battery, phone battery, or "accumulator", think secondary. If it's a torch or remote-control battery you throw away, think primary.