| LIST-I (Cell) | LIST-II (Use/Property/Reaction) |
|---|---|
| A. Leclanche cell | IV. Reaction at anode Zn → Zn2+ + 2e- |
| B. Ni-Cd cell | III. Rechargeable |
| C. Fuel cell | I. Converts energy of combustion into electrical energy |
| D. Mercury cell | II. Does not involve any ion in solution and is used in hearing aids |
In this question, we need to match the cells listed in List-I with their corresponding uses, properties, or reactions from List-II. Let's analyze each one:
Therefore, the correct answer is A-IV, B-III, C-I, D-II, which matches each cell type from List-I with the correct description or use from List-II.
A. Leclanche Cell: This is a primary cell where the reaction at the anode is: \[ \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \] Thus, it matches IV.
B. Ni-Cd Cell: The nickel-cadmium cell is a rechargeable secondary cell commonly used in portable devices. Thus, it matches III.
C. Fuel Cell: Fuel cells convert the energy of combustion (e.g., hydrogen and oxygen) into electrical energy. Thus, it matches I.
D. Mercury Cell: Mercury cells are small, primary cells commonly used in hearing aids, and they do not involve any ion in solution.Thus, it matches II.
Final Match: A-IV, B-III, C-I, D-II.


Electricity is passed through an acidic solution of Cu$^{2+}$ till all the Cu$^{2+}$ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is ___ mL. (Nearest integer)
Given:
$\mathrm{Cu^{2+} + 2e^- \rightarrow Cu(s)}$
$\mathrm{O_2 + 4H^+ + 4e^- \rightarrow 2H_2O}$
Faraday constant = 96500 C mol$^{-1}$
Molar volume at STP = 22.4 L
Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).

Method used for separation of mixture of products (B and C) obtained in the following reaction is: 