How many of the following are secondary cells?
Leclanche cell (dry cell), mercury cell, lead storage battery, nickel-cadmium cell
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2
In a primary cell the reaction occurs only once; after use the cell is dead and cannot be used again. A secondary cell can be recharged by passing current through it in the opposite direction, and then used again.
Secondary cells:
Lead storage battery (on charging, the cell reaction is reversed)
Nickel-cadmium cell (longer life than the lead storage cell)
Not secondary cells:
Leclanche cell (dry cell) — primary cell; it cannot be reused.
Mercury cell — primary cell, used in hearing aids and watches.
Secondary cells: 2.
NCERT (2026-27 edition):
2.6.1 Primary Batteries – “In the primary batteries, the reaction occurs only once and after use over a period of time battery becomes dead and cannot be reused again. The most familiar example of this type is the dry cell (known as Leclanche cell after its discoverer)…”
“Mercury cell, …suitable for low current devices like hearing aids, watches, etc.…”
2.6.2 Secondary Batteries – “A secondary cell after use can be recharged by passing current through it in the opposite direction so that it can be used again. …The most important secondary cell is the lead storage battery…”
“Another important secondary cell is the nickel-cadmium cell… which has longer life than the lead storage cell but more expensive to manufacture.”