Prelims 2015 · archive
EasyWith reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements:
- 1.If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
- 2.Fuel cells can be used for powering buildings and not for small devices like laptop computers.
- 3.Fuel cells produce electricity in the form of Alternating Current (AC).
Which of the statements given above is/are correct?
Answer & explanation
Answer: (a) 1 only
With pure hydrogen, a fuel cell's only products are electricity, water and heat, so statement 1 is correct. Fuel cells power everything from buildings to laptops, so statement 2 is wrong. A fuel cell produces direct current (DC), not AC, so statement 3 is wrong. The answer is (a) 1 only.
- ✓ 1. Hydrogen reacts with oxygen to produce electricity, with water and heat as the only by-products when the fuel is pure hydrogen.
- ✗ 2. Fuel cells can power systems as large as a utility power station and as small as a laptop computer, so they are not limited to buildings.
- ✗ 3. A fuel cell produces direct current (DC), in which electrons flow in only one direction. To supply AC, its output must be converted by an inverter.
Remember · A hydrogen fuel cell gives DC electricity, with water and heat as the only by-products. It works at every scale, from laptops to power stations.
Sources
- US Department of Energy – Fuel Cells ↗ “If hydrogen is the fuel, the only products are electricity, water, and heat. … can provide power for systems as large as a utility power station and as small as a laptop computer.”
- US Department of Energy – Fuel Cell Systems ↗ “Fuel cells produce electricity in the form of direct current (DC). In a DC circuit, electrons flow in only one direction.”
Question: UPSC Civil Services (Preliminary) 2015, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·