Chapter-13 Nuclei — Online MCQ Test
PHYSICS · CLASS 12 SECOND PUC · Karnataka State Board
Practice Chapter-13 Nuclei with a free chapter-wise online MCQ test.
This chapter covers: nucleus - mass defect - binding energy - nuclear fission - nuclear fusion.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-13 Nuclei — Important Questions & Answers
The nucleus of an atom contains which of the following particles?
- A. Protons and neutrons only
- B. Protons, neutrons, and electrons
- C. Electrons and neutrons only
- D. Only protons
Answer: A. Protons and neutrons only
The nucleus contains protons (positively charged) and neutrons (neutral particles). Electrons orbit outside the nucleus in electron shells.
The nucleus contains protons (positively charged) and neutrons (neutral particles). Electrons orbit outside the nucleus in electron shells.
Mass defect is defined as:
- A. The difference between the sum of individual nucleon masses and the actual nuclear mass
- B. The total mass of the nucleus
- C. The mass of electrons in an atom
- D. The difference between proton mass and neutron mass
Answer: A. The difference between the sum of individual nucleon masses and the actual nuclear mass
Mass defect (Δm) = (Z×mₚ + N×mₙ) - M, where the actual nuclear mass is less than the sum of individual nucleon masses due to binding energy.
Mass defect (Δm) = (Z×mₚ + N×mₙ) - M, where the actual nuclear mass is less than the sum of individual nucleon masses due to binding energy.
Which of the following is NOT a characteristic of nuclear binding energy?
- A. It is the energy required to disassemble a nucleus into separate nucleons
- B. It increases linearly with mass number for all nuclei
- C. It is related to mass defect through E = mc²
- D. It represents the stability of a nucleus
Answer: B. It increases linearly with mass number for all nuclei
Binding energy does not increase linearly with mass number. The binding energy per nucleon reaches maximum around A = 56, then decreases for heavier nuclei.
Binding energy does not increase linearly with mass number. The binding energy per nucleon reaches maximum around A = 56, then decreases for heavier nuclei.
The nuclear force between nucleons is characterized by which property?
- A. It is always repulsive, like electromagnetic force
- B. It is strongly attractive at short distances but repulsive at very short distances
- C. It is inversely proportional to distance, like gravity
- D. It only acts between protons and neutrons, not within neutrons
Answer: B. It is strongly attractive at short distances but repulsive at very short distances
The strong nuclear force is attractive at distances of ~1-3 fm but becomes repulsive at distances less than 0.5 fm, maintaining nuclear stability.
The strong nuclear force is attractive at distances of ~1-3 fm but becomes repulsive at distances less than 0.5 fm, maintaining nuclear stability.
Consider the binding energy curve. A nucleus at the left side (light nuclei) undergoes fusion, and one at the right side (heavy nuclei) undergoes fission. Which process releases more energy per nucleon involved?
- A. Fusion, because light nuclei combine to approach maximum BE/A region
- B. Fission, because it involves heavier, more tightly bound nuclei
- C. Both release equal energy per nucleon
- D. Depends on the specific nuclei involved
Answer: A. Fusion, because light nuclei combine to approach maximum BE/A region
Light nuclei fusion moves nuclei toward A≈56 (maximum BE/A ≈ 8.8 MeV), while heavy nuclei fission also moves toward this region but from the opposite side. Fusion of very light nuclei releases more energy per nucleon.
Light nuclei fusion moves nuclei toward A≈56 (maximum BE/A ≈ 8.8 MeV), while heavy nuclei fission also moves toward this region but from the opposite side. Fusion of very light nuclei releases more energy per nucleon.