Question

Which of the following is a drawback to use of hydrogen fuel cells?
(A)- Do not work at low temperature
(B)- Requires catalyst
(C)- It does not have any drawbacks
(D)- Both A and B

Answer 1

A fuel cell (hydrogen fuel cell) is an electrochemical cell that converts chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a couple of redox reactions.

Complete answer:
First, let's have an idea about how fuel cells work.
Fuel cells efficiently convert chemical energy from hydrogen-rich fuels into electrical power and high-quality heat via an electrochemical process that is efficient and emits water rather than pollutants as there is no burning of the fuel keeping the environment safe.
Hydrogen fuel cells are cells that contain hydrogen as the fuel. Hydrogen fuel is a zero-emission fuel that releases energy during combustion or through certain electrochemical reactions. Fuel cells and batteries produce an electric current through a chemical reaction, but a fuel cell will produce energy if there is supply of fuel, thus never losing its charge.
Hydrogen is the simplest and the most abundant element in the universe. Despite its abundance, hydrogen is rarely found in its naked (pure) form. Water is the major source of hydrogen, hydrocarbons being the next in line in sources for hydrogen. Hydrogen can be extracted from its sources quite easily from both renewable and non-renewable sources.
The basic construction of a hydrogen fuel cell consists of two electrodes, an electrolyte, a fuel (hydrogen) and a power supply. An electrolyte that separates the two electrodes is an ion conducting material which facilitates the free passage of ions through it. In a fuel cell, an oxidizing agent (or oxygen) is made to flow through the fuel (i.e. hydrogen). Hydrogen and oxygen combine to form water and generate heat. At the anode, hydrogen is stripped of its electron and its proton passes through the electrolyte. The electron is made to pass through an external DC circuit to power devices.
Some advantages of hydrogen fuel cells are that its fuel is an abundant resource, it does not emit harmful emissions, it also has high efficiency, hydrogen is a renewable source of energy.
But everything comes with some disadvantages and in this case hydrogen fuel cells are expensive, storage of hydrogen is difficult, hydrogen is highly flammable, it does not work in low temperature, it requires a catalyst to work etc.

From the above discussion, it is clear that the answer to the above question is option (D).

Note:
It is important to note that fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from metals and their ions that are already present in the battery.