Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?
Answer & explanation
Answer: (d) Water vapour
A hydrogen fuel cell combines hydrogen from the tank with oxygen from the air to produce electricity for the motor. The only chemical product of that reaction is water (H2O), so the tailpipe of a fuel-cell car releases just water vapour and some warm air, with no smog-forming pollutants.
- ✓ (d) At the cathode, the hydrogen ions, the electrons that have passed through the circuit and oxygen join to form water, which leaves as vapour.
- ✗ (c) Oxygen is consumed by the fuel cell, not given out; it is taken in from the air as a reactant.
- ✗ (a) Hydrogen peroxide (H2O2) is not a product of a fuel cell's hydrogen–oxygen reaction; the cell is designed to yield plain water.
Remember · Hydrogen fuel cell: 2H2 + O2 → 2H2O + electricity + heat. FCEV tailpipe emits only water vapour and warm air.
Sources
- US Department of Energy, Alternative Fuels Data Center: Fuel Cell Electric Vehicles ↗ “They are more efficient than conventional internal combustion engine vehicles and produce no harmful tailpipe pollutants—they only emit water vapor and warm air.”
- US Department of Energy: Fuel Cells ↗ “A fuel cell uses the chemical energy of hydrogen or other fuels to efficiently produce electricity. If hydrogen is the fuel, the only products are electricity, water, and heat.”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·