Hydrogen as a Fuel - UNSOLVED PRACTICE SET
Chapter: Hydrogen | Topic: Hydrogen as a Fuel
HYDROGEN AS A FUEL - UNSOLVED PRACTICE SET
Topic: Hydrogen as a Fuel
Multiple Choice Questions
Q1. The main advantage of hydrogen as a fuel is that its combustion produces:
- Carbon dioxide and water
- Only water
- Carbon monoxide and water
- Sulphur dioxide and water
Q2. A hydrogen fuel cell converts:
- Chemical energy directly into electrical energy
- Electrical energy into chemical energy
- Heat energy into electrical energy
- Nuclear energy into electrical energy
Q3. The calorific value of hydrogen is approximately:
- 120 kJ/g
- 142 kJ/g
- 50 kJ/g
- 280 kJ/g
Q4. Which of the following is a major challenge in using hydrogen as a fuel?
- It is not abundant in nature
- It is difficult to store and transport safely
- It produces toxic emissions
- It has a very low calorific value
Q5. In a hydrogen-oxygen fuel cell, the reaction at the anode is:
- O₂ + 2H₂O + 4e⁻ → 4OH⁻
- H₂ + 2OH⁻ → 2H₂O + 2e⁻
- 2H₂ + O₂ → 2H₂O
- H₂O → H₂ + ½O₂
Q6. Hydrogen is considered a "secondary fuel" or "energy carrier" because:
- It is found freely in nature
- It must be produced from other sources using energy
- It is more expensive than petrol
- It cannot be used in vehicles
Short Answer Questions
Q7. Write the balanced chemical equation for the combustion of hydrogen. Why is this reaction considered environmentally friendly compared to burning fossil fuels?
Q8. Explain the working principle of a hydrogen-oxygen fuel cell. What are the products at the anode and cathode?
Q9. Why does hydrogen have a higher calorific value than petrol or diesel? What does this mean in practical terms for vehicles?
Q10. List two advantages and two disadvantages of using hydrogen as a fuel for vehicles in Indian cities like Delhi and Mumbai.
Q11. Your school is planning to replace its diesel generator with a hydrogen fuel cell system. What infrastructure changes would be needed to make this possible?
Q12. ISRO (Indian Space Research Organisation) uses liquid hydrogen as fuel in its rockets. Why is liquid hydrogen preferred over gaseous hydrogen for rocket propulsion?
Long Answer Questions
Q13. Discuss hydrogen as a future fuel under the following headings:
(a) Environmental benefits (zero carbon emissions)
(b) High energy content per unit mass
(c) Methods of production (electrolysis, steam reforming, biomass)
(d) Current limitations and challenges
Give examples of countries or companies already using hydrogen fuel.
Q14. Explain the construction and working of a hydrogen-oxygen fuel cell with a labelled diagram. Include:
(a) The electrolyte used (acidic or alkaline)
(b) Reactions at anode and cathode
(c) The overall cell reaction
(d) Why fuel cells are more efficient than internal combustion engines
Q15. India has launched the National Hydrogen Mission to promote green hydrogen. Discuss:
(a) What is "green hydrogen" and how is it different from "grey hydrogen" and "blue hydrogen"
(b) Why India is investing in green hydrogen for its energy security
(c) The potential applications of hydrogen in India (transport, industry, power generation)
(d) One major technical and one economic barrier India needs to overcome
Numerical / Application-Based Problems
Q16. The enthalpy of combustion of hydrogen is -286 kJ/mol.
(a) Calculate the energy released when 10 g of hydrogen is completely burnt.
(b) Calculate the mass of water produced in this reaction.
(c) If this energy is used to heat 100 kg of water, calculate the rise in temperature of water.
[Given: Specific heat capacity of water = 4.18 J/g°C, Molar mass of H₂ = 2 g/mol, H₂O = 18 g/mol]
Q17. A hydrogen fuel cell bus in Delhi carries 20 kg of hydrogen gas in its tanks.
(a) Calculate the total energy available from this hydrogen if the calorific value is 142 kJ/g.
(b) If the fuel cell is 60% efficient, calculate the actual usable energy.
(c) Compare this with a diesel bus carrying 100 kg of diesel (calorific value = 45 kJ/g, engine efficiency = 30%). Which bus can travel farther, and by what factor?
[Express your answer in terms of usable energy per kg of fuel]
Q18. India aims to produce 5 million tonnes of green hydrogen annually by 2030. Green hydrogen is produced by electrolysis of water using renewable energy.
(a) Write the overall reaction for the electrolysis of water.
(b) If producing 1 kg of hydrogen requires 50 kWh of electricity, calculate the total electricity needed for 5 million tonnes of hydrogen.
(c) If solar power costs ₹ 3 per kWh, calculate the total electricity cost. Why is this investment considered worthwhile despite the high initial cost?