Question map
Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen ?
Explanation
Fuel-cell-powered vehicles have very high energy conversion efficiency, and near-zero pollution, with CO₂ and water vapor being the only emissions.[1] More specifically, fuel cell vehicles produce no harmful tailpipe emissions—they only emit water [2]vapor and warm air. Emissions from a fuel cell electric vehicle on pure hydrogen are limited to only[3] water. In a hydrogen fuel cell, hydrogen reacts with oxygen from the air in an electrochemical process that generates electricity to power the vehicle's motor. The only byproduct of this reaction is water, which is released as water vapor through the exhaust. This makes hydrogen fuel cell vehicles an environmentally friendly transportation option with zero harmful emissions at the point of use. Options A (hydrogen peroxide), B (hydronium), and C (oxygen) are not emitted from fuel cell vehicles.
Sources- [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for automobile transport > p. 296
- [2] https://afdc.energy.gov/vehicles/fuel-cell
- [3] https://www.oecd.org/content/dam/oecd/en/publications/reports/2004/03/can-cars-come-clean_g1gh419d/9789264104976-en.pdf
PROVENANCE & STUDY PATTERN
Full viewThis is a classic 'Sitter' that rewards reading standard static material (Shankar IAS) over chasing obscure current affairs. The question tests the fundamental chemical equation of a fuel cell ($2H_2 + O_2 \rightarrow 2H_2O$). If you know the input, the output is obvious.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Statement 1: Are hydrogen peroxide (H2O2) emitted from the exhaust of hydrogen-powered Fuel Cell Electric Vehicles (FCEVs)?
- Statement 2: Are hydronium ions (H3O+) emitted from the exhaust of hydrogen-powered Fuel Cell Electric Vehicles (FCEVs)?
- Statement 3: Is oxygen (O2) emitted from the exhaust of hydrogen-powered Fuel Cell Electric Vehicles (FCEVs)?
- Statement 4: Is water vapor (H2O) emitted from the exhaust of hydrogen-powered Fuel Cell Electric Vehicles (FCEVs)?
- Explicitly describes fuel-cell-powered vehicles as having near-zero pollution, listing CO2 and water vapor as the only emissions.
- By naming only CO2 and water vapour as exhaust products, it implies other reactive species (for example H2O2) are not emitted from the fuel-cell exhaust.
- Directly compares fuel-cell vehicles to internal combustion engines to highlight absence of typical combustion pollutants.
- Explicitly states FCEVs produce no harmful tailpipe emissions and identifies what is emitted.
- Says the only tailpipe outputs are water vapor and warm air, which excludes other exhaust species.
- Specifies the emissions from a pure-hydrogen fuel cell electric vehicle.
- States emissions are limited to only water, implying other chemical species are not emitted.
- Describes fuel cell vehicles as having zero tailpipe emissions, supporting the claim of only benign outputs.
- Reinforces that FCEV exhaust is not expected to contain additional pollutants or unusual ionic species.
States that hydrogen ions cannot exist alone and in the presence of water must be represented as H+ (aq) or hydronium ion (H3O+).
A student could combine this with the physical distinction between gaseous water vapor and liquid/aqueous water to ask whether exhaust water is present as an aqueous phase where H3O+ can exist.
Says fuel-cell-powered vehicles emit 'water vapor' as the (near-zero pollution) exhaust product.
A student could use this plus the rule that hydronium is an aqueous ion to consider whether gaseous exhaust water would need to condense or dissolve in ambient moisture to form H3O+.
Contains questions about how dilution affects hydronium ion concentration, emphasizing that hydronium is a property of aqueous (dissolved) acidic solutions.
A student could extend this to suggest measuring pH of condensed exhaust water (not the vapor) to detect hydronium concentration.
Explains that acidic/basic behaviour and ions (H+ / OH–) are phenomena of substances in solution (water), linking acidity to dissolved ions.
A student could infer that to have H3O+ emitted/transported, an aqueous medium must be present; thus check whether exhaust contains liquid aerosol/condensate that can host ions.
Shows that reactions of gases with water (e.g., CO2 + H2O forming H+ + HCO3–) produce hydrogen ions only in aqueous phase.
A student might analogously consider whether any reactive gas in exhaust could produce H+ only after dissolving in water droplets, suggesting sampling condensed exhaust for ionic content.
- Explicitly describes fuel-cell-powered vehicles as having near-zero pollution with water vapour (and CO2) listed as the emissions.
- Identifies water vapour as an exhaust product of fuel-cell-powered vehicles, implying O2 is not listed among emissions.
- Explains redox behaviour where hydrogen gains oxygen and is oxidised to form water (H2 → H2O).
- Shows oxygen is consumed in forming water from hydrogen, so oxygen is used up rather than emitted as O2.
- Explicitly states fuel-cell-powered vehicles have near-zero pollution with CO2 and water vapour as the only emissions.
- Directly links fuel-cell vehicle operation to water vapour being emitted.
- Defines water vapour as the gaseous form of water, clarifying that an emission described as 'water vapour' is gaseous H2O.
- Provides the basic chemical/physical identity needed to interpret 'water vapour' in exhaust context.
- Lists fuel-cells among non-conventional/renewable energy technologies, establishing relevance of fuel-cell vehicles in energy discussions.
- Supports context that fuel-cell technology is the vehicle class under consideration for emissions.
- [THE VERDICT]: Sitter. Direct hit from Shankar IAS (Ch 22: Renewable Energy) and basic NCERT Science logic.
- [THE CONCEPTUAL TRIGGER]: Green Mobility & Alternative Fuels. Specifically, the 'Input-Process-Output' mechanism of Hydrogen Fuel Cells.
- [THE HORIZONTAL EXPANSION]: Memorize the Fuel Cell ecosystem: 1) Inputs: $H_2$ (Anode) + $O_2$ (Cathode). 2) Catalyst: Platinum (expensive, sensitive to CO poisoning). 3) Electrolyte: Polymer Electrolyte Membrane (PEM). 4) Byproducts: Water, Heat, Electricity. 5) Colors of Hydrogen: Green (Electrolysis), Blue (SMR + CCS), Grey (SMR), Pink (Nuclear).
- [THE STRATEGIC METACOGNITION]: Do not just memorize 'Hydrogen is good'. Visualize the chemical reaction. For every energy tech (Nuclear, Coal, Biofuel), create a mental table: What goes in? What comes out? What is the residue?
Fuel-cell-powered vehicles emit primarily carbon dioxide and water vapour, not combustion-generated oxidants like hydrogen peroxide.
High-yield for environment and transport questions: helps distinguish pollution profiles of fuel-cell vs internal-combustion vehicles, informs answers on low-emission technologies and urban air quality policy. Useful for questions on clean mobility choices and emission inventories.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for automobile transport > p. 296
Hydrogen peroxide is discussed as a tropospheric oxidant produced via atmospheric photochemistry, not as a typical vehicle exhaust constituent.
Important for questions on atmospheric chemistry and air quality impacts: connects ozone depletion/UV effects to oxidant formation and public health consequences; enables answers on secondary pollutant formation versus direct emissions.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > Effects on air quatity > p. 272
Shifting to fuel-cell and electric vehicles is presented as a measure to reduce urban pollutants such as SPM and SO2, reinforcing that such technologies lower direct exhaust pollutants.
Valuable for policy and environment mains/GS answers: links technological choices (CNG, EVs, FCEVs) to urban air-quality outcomes and mitigation strategies; supports formulation of policy recommendations and comparative evaluation questions.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 23: India and Climate Change > 23.r3.r. Clean Air Initiatives > p. 315
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for automobile transport > p. 296
Hydronium (H3O+) represents a proton combined with water and is the form hydrogen ions take in water.
Understanding that H3O+ is an aqueous ionic species is high-yield for acid–base chemistry questions and for distinguishing chemical species by phase (aqueous vs gaseous). This concept links to electrochemistry, environmental chemistry, and interpreting statements about emissions or pollutants.
- Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Activity 2.9 > p. 23
- Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > QUESTIONS > p. 25
Hydrogen fuel cells produce water vapor as a main exhaust product rather than releasing aqueous ions.
This is essential for questions on clean-transport technologies, emission profiles of alternate fuels, and policy debates on air quality. It helps compare pollution impacts of different vehicle technologies and evaluate claims about specific pollutants.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for automobile transport > p. 296
- Indian Economy, Nitin Singhania .(ed 2nd 2021-22) > Chapter 21: Sustainable Development and Climate Change > National Hydrogen Energy Mission (NHM) - announced in Union Budget 2021-22 > p. 605
Hydrogen and hydroxide ions are produced in water and are responsible for acidic/basic conductivity, implying ions are tied to the aqueous phase.
Mastering the role of ions in solution aids in reasoning about where ions can exist (solution vs gas), which is useful across physical chemistry, environmental science, and technology questions involving emissions, water chemistry, and electrochemical devices.
- Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > What you have learnt > p. 33
- Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Activity 2.9 > p. 23
Fuel-cell electric vehicles primarily emit water vapour as their exhaust product rather than molecular oxygen.
High-yield for questions on clean-transport technology and pollution control; links technology descriptions to policy debates on urban air quality and vehicle adoption. Enables answering questions about comparative emissions of different vehicle types and implications for air pollution.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > Fuel cells for automobile transport > p. 296
The 'Next Logical Question' will likely target the Catalyst or Electrolyte. Expect a question on 'PEMFC' (Proton Exchange Membrane Fuel Cell) using Platinum catalysts, or the issue of 'Carbon Monoxide poisoning' of the platinum catalyst in hydrogen fuel cells.
Apply 'Stability Logic'. A vehicle exhaust releases stable molecules, not reactive ions or oxidizers. Hydrogen Peroxide ($H_2O_2$) is unstable/reactive. Hydronium ($H_3O^+$) is an ion that exists in liquid water, not a gas pipe emission. Oxygen is the fuel input. Water vapour is the only stable, neutral combustion product.
Link to GS-3 (Energy Security & Economy): Green Hydrogen is crucial not just for cars (FCEVs) but for decarbonizing 'Hard-to-Abate' sectors like Steel and Shipping (where batteries fail). It directly impacts India's Current Account Deficit by reducing crude imports.