Question 1: Explain in your own words what nuclear fission is and how it releases energy.

Answer: Nuclear fission is a process where a heavy nucleus, such as uranium-235, splits into smaller nuclei, releasing a large amount of energy, neutrons, and gamma rays.

Question 1: Describe the role of neutrons in initiating nuclear fission.

Answer: Neutrons are absorbed by a fissile nucleus like uranium-235, causing it to become unstable and split into smaller nuclei, releasing energy and more neutrons.

Question 2: What is the significance of chain reactions in nuclear fission?

Answer: Chain reactions occur when the neutrons released by one fission event trigger additional fissions, leading to a self-sustaining release of energy.

Question 1: Calculate the energy released when 1 kg of uranium-235 undergoes fission. (Use the approximate energy released per fission as 200 MeV).

Answer: Energy (J) = Number of atoms × energy per fission (J). Number of atoms = (mass / molar mass) × Avogadro's number. Molar mass of uranium-235 ≈ 235 g/mol. Number of atoms = (1000 g / 235 g/mol) × 6.022×10^23 ≈ 2.56×10^24 atoms. Total energy = 2.56×10^24 atoms × 200 MeV per atom × 1.602×10^−13 J/MeV ≈ 8.18×10^13 Joules.

Question 2: If a nuclear power plant produces 3×10^12 Joules of energy daily, approximately how many fission events are needed per day?

Answer: Number of fissions = Total energy / energy per fission = 3×10^12 J / (200 MeV × 1.602×10^−13 J/MeV) ≈ 9.36×10^24 fissions.

Question 1: List three safety precautions that must be taken when handling fissile materials like uranium-235 in a laboratory setting.

Answer: Use of protective shielding, proper storage in secure containers, and limiting exposure time to prevent radiation harm.

Question 2: Describe a simple experimental setup to demonstrate the concept of nuclear fission without actual radioactive materials.

Answer: A classroom demonstration could involve using a model or simulation to show how a neutron strikes a fissile nucleus causing it to split, illustrating chain reactions and energy release through animations or physical props.

Question 1: A reactor uses 50 kg of uranium-235. How much energy can be theoretically produced if all fissile material is converted? (Use previous calculation method).

Answer: Number of atoms = (50,000 g / 235 g/mol) × 6.022×10^23 ≈ 1.28×10^24 atoms. Total energy = 1.28×10^24 × 200 MeV × 1.602×10^−13 ≈ 2.58×10^13 Joules.

Question 2: Explain why controlling the rate of fission reactions is critical in nuclear power plants.

Answer: To prevent runaway reactions that could lead to overheating or meltdowns, and to maintain a steady, safe release of energy.

Question 1: Describe how nuclear fission is utilised in commercial nuclear power plants to generate electricity.

Answer: Nuclear fission in reactors produces heat, which is used to generate steam that drives turbines connected to electricity generators.

Question 2: Identify one advantage and one disadvantage of using nuclear fission as an energy source.

Answer: Advantage: Produces a large amount of energy with low greenhouse gas emissions. Disadvantage: Produces radioactive waste that requires secure disposal.