Question

Which of the following statements are correct about a dry cell?

• [(I)] It is also known as Leclanche cell.

• [(II)] Electrolyte is a moist paste of \(NH_4Cl\) and \(ZnCl_2\).

• [(III)] Reaction at cathode is \[ MnO_2 + NH_4^+ + e^- \rightarrow MnO(OH) + NH_3 \]

• [(IV)] It can be charged.

• A. I, II, III only
• B. II, III, IV only
• C. I, III, IV only
• D. I, II, IV only

Hint:

Remember the simple rule:

• Dry cell = Primary cell = Not rechargeable.

• Lead-acid battery and Ni-Cd battery = Secondary cells = Rechargeable.
Whenever a question asks whether a dry cell can be charged, the answer is always No.

Answer 1

The Correct Option is A

Step 1: Know what a dry cell is.
A dry cell is the common battery used in torches, clocks and remotes. It is a primary cell, which means it gives current by a one-way reaction and cannot be recharged.

Step 2: Check statement (I).
The dry cell is indeed the well-known Leclanche cell. So statement (I) is true.

Step 3: Check statement (II).
The electrolyte is a wet paste of ammonium chloride ($NH_4Cl$) and zinc chloride ($ZnCl_2$). This matches the real cell, so statement (II) is true.

Step 4: Check statement (III).
At the carbon (cathode) the reaction is $MnO_2 + NH_4^+ + e^- \rightarrow MnO(OH) + NH_3$. This is the correct cathode reaction, so statement (III) is true.

Step 5: Check statement (IV).
A dry cell is a primary cell. Its reaction is not easily reversed, so it cannot be recharged. Hence statement (IV) is false.

Step 6: Combine the results.
True statements are (I), (II) and (III). The false one is (IV).

Step 7: State the final answer.
The correct combination is:
\[ \boxed{\text{I, II, III only}} \]