Fuel cells are electrochemical devices that convert the chemical energy of a fuel, such as hydrogen, into electrical energy through an oxidation-reduction (redox) reaction.
Catalysts are used to facilitate the redox reactions occurring at the electrodes of the fuel cell. Platinum and palladium are commonly used as catalysts in fuel cells due to their high catalytic activity, stability, and resistance to corrosion.
Therefore, the correct answer is (B) Platinum - Palladium.
Platinum (Pt) and Palladium (Pd) are used as catalysts in fuel cells because of their high efficiency in facilitating the redox reactions. Platinum, especially, acts as a catalyst for both the hydrogen oxidation at the anode and the oxygen reduction at the cathode.
These metals provide an active surface for the electrochemical reaction, improving the performance and efficiency of the fuel cell.
Correct Answer: Platinum - Palladium


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
Match the following:
In the following, \( [x] \) denotes the greatest integer less than or equal to \( x \). 
Choose the correct answer from the options given below:
For x < 0:
f(x) = ex + ax
For x ≥ 0:
f(x) = b(x - 1)2