Nuclear Energy – Fission & Fusion - UNSOLVED PRACTICE SET
Chapter: Sources of Energy | Topic: Nuclear Energy Fission and Fusion
NUCLEAR ENERGY – FISSION & FUSION - UNSOLVED PRACTICE SET
Topic: Nuclear Energy Fission and Fusion
Multiple Choice Questions
Q1. In a nuclear fission reaction, a heavy nucleus splits into:
- Two lighter nuclei with release of energy
- Two heavier nuclei with absorption of energy
- One lighter and one heavier nucleus with no energy change
- Multiple electrons and protons only
Q2. Nuclear fusion is the process in which:
- A heavy nucleus splits into lighter nuclei
- Two lighter nuclei combine to form a heavier nucleus
- Electrons are removed from an atom
- Neutrons are converted into protons
Q3. Which of the following is used as a fuel in nuclear power plants?
- Coal
- Uranium-235
- Natural gas
- Hydrogen gas
Q4. The main advantage of nuclear energy over fossil fuels is that:
- It produces much more air pollution
- It releases harmful greenhouse gases
- A very small amount of fuel produces a huge amount of energy
- It is very cheap and easily available everywhere
Q5. In a nuclear reactor, control rods are made of cadmium because cadmium:
- Speeds up the fission reaction
- Absorbs neutrons and slows down the chain reaction
- Reflects neutrons back into the reactor
- Converts nuclear energy directly into electrical energy
Q6. Nuclear fusion reactions are not yet used for commercial power generation mainly because:
- The fuel (hydrogen) is not available on Earth
- The reaction requires extremely high temperatures and pressures that are difficult to achieve and maintain
- Fusion produces very little energy compared to fission
- Fusion reactions release dangerous radioactive waste
Short Answer Questions
Q7. Define nuclear fission. Write the name of one element commonly used as fuel in nuclear reactors.
Q8. What is a chain reaction in the context of nuclear fission? Why is it important to control this reaction in a nuclear power plant?
Q9. Differentiate between nuclear fission and nuclear fusion on the basis of:
(i) Temperature requirement
(ii) Nature of products formed
Q10. Why is the disposal of nuclear waste considered a major problem? Mention one method currently used for storing nuclear waste.
Q11. A student reads that "the energy released in the fission of one atom of uranium-235 is about 10 million times the energy released in burning one atom of carbon." Explain why nuclear fuel has such high energy density compared to chemical fuels.
Q12. Name the main components of a nuclear power reactor and state the function of any two of them.
Long Answer Questions
Q13. Describe the process of nuclear fission with a labelled diagram description. Explain how energy is released during this process and how it is converted into electrical energy in a nuclear power plant.
Q14. The Sun produces enormous energy through nuclear fusion. Explain the proton-proton chain reaction that occurs in the Sun. Why can't we use this same process to generate electricity on Earth at present? Discuss the challenges scientists face in achieving controlled nuclear fusion.
Q15. The Chernobyl disaster (1986) and the Fukushima accident (2011) raised serious concerns about nuclear safety. Analyse the risks associated with nuclear power plants. In your opinion, should countries like India continue to invest in nuclear energy? Give balanced arguments for and against, considering energy needs, safety, and environmental concerns.
Numerical / Application-Based Problems
Q16. A nuclear power plant uses uranium-235 as fuel. If fission of one uranium-235 nucleus releases approximately 200 MeV of energy, calculate the energy released (in joules) when 1 mole of uranium-235 undergoes fission.
(Given: 1 eV = 1.6 × 10⁻¹⁹ J, Avogadro's number = 6.022 × 10²³)
Q17. A nuclear reactor produces 1000 MW of power. Calculate:
(a) The energy produced in one hour (in MJ)
(b) If the efficiency of converting nuclear energy to electrical energy is 33%, how much nuclear energy is actually consumed in one hour?
Q18. In a hypothetical fusion reaction, 4 hydrogen nuclei (protons) combine to form 1 helium nucleus. The mass of one hydrogen nucleus is 1.0078 u and the mass of one helium nucleus is 4.0026 u.
(a) Calculate the mass defect in this reaction.
(b) Using Einstein's equation E = mc² (where 1 u = 931.5 MeV/c²), calculate the energy released in this fusion reaction.