WBBSE Class 10 Physical Science Notes Chapter 7 (Atomic Nucleus) IN ENGLISH | Atomic nucleus
WBBSE Class 10 Physical Science Notes Chapter 7 (Atomic Nucleus) IN ENGLISH | Atomic nucleus
Very Short Answer Type Questions:
**1. Hand Rays:**
- *Which type of radiation is referred to as hand rays?*
- **Answer:** γ-rays
**2. Maximum Tissue Damage:**
- *Among α, β, and γ-rays, which causes maximum damage to body tissues?*
- **Answer:** α-rays
**3. Nucleus Density:**
- *What is the density of the nucleus?*
- **Answer:** \(10^{14} \, \text{cm}^{-3}\)
**4. Binding Energy for Mass Defect:**
- *What is the binding energy for a mass defect of 1 amu?*
- **Answer:** 931.5 MeV
**5. \(n/p\) Ratio for Lighter Nuclides:**
- *What is the \(n/p\) ratio for lighter nuclides (\(Z\) up to 20)?*
- **Answer:** 1
**6. \(n/p\) Ratio for \(^{11}H\):**
- *What is the \(n/p\) ratio for \(^{11}H\)?*
- **Answer:** 0
**7. \(n/p\) Ratio for \(^{209}_{83}Bi\):**
- *What is the \(n/p\) ratio for \(^{209}_{83}Bi\)?*
- **Answer:** 1.52
**8. Emission Increasing \(n/p\) Ratio:**
- *Which type of emission increases the \(n/p\) ratio?*
- **Answer:** Positron emission
**9. Emission Decreasing \(n/p\) Ratio:**
- *Which type of emission decreases the \(n/p\) ratio?*
- **Answer:** β-ray emission
**10. Packing Fraction for Stable Nuclides:**
- *write down the value of the packing fraction for stable nuclides?*
- **Answer:** Zero or negative
**11. Packing Fraction for Unstable Nuclides:**
- *write down the value of the packing fraction for unstable nuclides?*
- **Answer:** Positive
**12. Magic Numbers:**
- *What are magic numbers in nuclear physics?*
- **Answer:** Magic numbers are 2, 8, 20, 50, 82, and 126, which represent stable configurations of nucleons.
**14. Cause of Nuclear Isomerism:**
- *What causes nuclear isomerism?*
- **Answer:** Nuclear isomerism arises due to differences in the arrangement and energy of nucleons.
**15. Rate of Nuclear Decay Independence:**
- *Is the rate of nuclear decay dependent on concentration, pressure, and temperature?*
- **Answer:** No, the rate of nuclear decay is independent of concentration, pressure, and temperature.
**16. Life Span of Radioactive Element:**
- *What is the life span of a radioactive element?*
- **Answer:** The life span of a radioactive element is infinite.
**17. Half-life Independence:**
- *Is the half-life of a radioactive element dependent on its physical and chemical state?*
- **Answer:** No, the half-life of a radioactive element is independent of its physical and chemical state.
**18. End Product of \(4n + 1\) Series:**
- *What is the end product of the \(4n + 1\) series?*
- **Answer:** Bismuth
**19. End Product of \(4n\) Series:**
- *What is the end product of the \(4n\) series?*
- **Answer:** Lead
**20. Neptunium Series Start:**
- *Why is the \(4n + 1\) series called the neptunium series even though it starts from plutonium?*
- **Answer:** The neptunium series starts from plutonium but is named after neptunium, the longest-lived isotope in the series.
**21. Starting Element of \(4n + 3\) Series:**
- *What is the starting element of the \(4n + 3\) series?*
- **Answer:** \(^{235}_{92}U\)
**22. Group Number Change during Emissions:**
- *Is there any change in the group number during α and β-emissions in lanthanides and actinides?*
- **Answer:** No, there is no change in the group number during α and β-emissions in lanthanides and actinides.
**23. α and β Particles from Thorium Series:**
- *How many α and β particles are emitted from the thorium series?*
- **Answer:** The thorium series emits 6 α and 4 β particles.
**24. α and β Particles from Uranium Series:**
- *How many α and β particles are emitted from the uranium series?*
- **Answer:** The uranium series emits 8 α and 6 β particles.
**25. Natural Radioactive Series:**
- *Name the natural radioactive series.*
- **Answer:** The natural radioactive series include the 4n, (4n+2), and (4n+3) series.
**26. Artificial Series:**
- *What is an artificial series?*
- **Answer:** The (4n+1) series is an artificial series.
**27. Cause of β-emission:**
- *What causes β-particle emission?*
- **Answer:** β-particle emission is due to the breaking down of a neutron into a proton and an electron.
**28. Nuclear Forces Relation with Electrostatic Forces:**
- *What is the relation of nuclear forces to electrostatic forces?*
- **Answer:** Nuclear forces are about \(10^{21}\) times as strong as electrostatic forces.
**29. \(n/p\) Ratio of \(^{3}_{1}H\):**
- *What is the \(n/p\) ratio of \(^{3}_{1}H\)?*
- **Answer:** The \(n/p\) ratio of \(^{3}_{1}H\) is 2.0.
**30. Energy Released in \(^{235}U\) Fission:**
- *How much energy is released during the fission of an atom of \(^{235}U\)?*
- **Answer:** The fission of an atom \(^{235}U\) releases 211.5 MeV of energy.
**31. Uses of Radioisotopes:**
- *What are the uses of P-32, Co-60, Na-24, I-131?*
- **Answer:**
- P-32: Leukemia (Blood cancer)
- Co-60: Treatment of tumors and cancer
- Na-24: Circulation of blood.
- I-131: Treatment of goiter (Hyperthyroidism)
**32. Thermonuclear Reactions:**
- *Why are nuclear fusion reactions termed as thermonuclear reactions?*
- **Answer:** Nuclear fusion reactions require very high temperatures (≈\(10^
6\) K), hence the term "thermonuclear."
**33. Types of Meson Particles:**
- *What are the types of meson particles?*
- **Answer:** The meson particles are positive meson (\(π^+\)), negative meson (\(π^-\)), and neutral meson (\(π^0\)).
**34. Factors Affecting Nucleus Stability:**
- *On what factors does the stability of the nucleus depend?*
- **Answer:** The stability of the nucleus is governed mainly by mass defects, binding energy, magic numbers, and \(n/p\) ratio.
**35. Conversion of Mass Defect into Energy:**
- *How can mass defect be converted into energy?*
- **Answer:** Mass defect can be converted into energy using Einstein's equation \(ΔE = mc^2\).
**36. Definition of Binding Energy:**
- *What is binding energy?*
- **Answer:** Binding energy is the energy that binds nucleons together, and binding energy per nucleon is used to compare the stability of various nuclei.
**37. Discoverer of Natural Radioactivity:**
- *Who discovered natural radioactivity?*
- **Answer:** Natural radioactivity was discovered by Henry Becquerel.
**38. Effect of α-particle Emission on Mass and Atomic Number:**
- *What is the effect of α-particle emission on mass and atomic number?*
- **Answer:** α-particle emission decreases the mass number by 4 units and decreases the atomic number by two units.
**39. Units of Rate of Decay:**
- *State different units of the rate of decay.*
- **Answer:**
- 1 Curie (\(c\)) = \(3.7 \times 10^{10}\) dps
- 1 Rutherford (\(Rd\)) = \(10^6\) dps
- 1 Becquerel (\(Bq\)) = 1 dps
**40. Use of Carbon Dating:**
- *What is the use of carbon dating?*
- **Answer:** Carbon dating is used to determine the age of wood, animal fossils, etc., containing carbon.
These answers provide concise information on various aspects of atomic nucleus and nuclear physics.
Short Answer Type Questions:
**1. Nuclear Reactions:**
- *What are nuclear reactions?*
- **Answer:** Nuclear reactions are the reactions in which nucleons of an atom undergo a change.
**2. Isotopes:**
- *What do you mean by ‘isotopes’?*
- **Answer:** Isotopes are atoms of an element with the same atomic number but different mass numbers.
- Examples: \(^1_1H, ^2_1H, ^3_1H\)
**3. Nuclear Isomers:**
- *What are nuclear isomers?*
- **Answer:** Nuclear isomers are nuclear species with the same atomic number and mass number but different radioactive properties.
- Examples: \(^{69}_{30}Zn\) (t1/2 = 13.8 hours) and \(^{69}_{30}Zn\) (t1/2 = 57 minutes)
**4. Isoster:**
- *What is an isoster?*
- **Answer:** Isosters are molecules or ions with the same number of atoms and electrons.
- Examples: N2O and CO2
**5. Nuclear Forces:**
- *What do you mean by nuclear forces?*
- **Answer:** Nuclear forces are the forces that hold nucleons together within the nucleus, existing among p-p, p-n, and n-n.
**6. Packing Fraction:**
- *Define packing fraction.*
- **Answer:** Packing fraction, proposed by Aston, is the difference between the actual isotopic mass and the mass number.
**7. Magic Numbers:**
- *Explain magic numbers.*
- **Answer:** Magic numbers (2, 8, 20, 50, 82, and 126) represent stable configurations of nucleons.
**8. Radioactivity:**
- *Define radioactivity.*
- **Answer:** Radioactivity is the spontaneous disintegration of the nucleus without external excitation.
**9. Group Displacement Law:**
- *What is the Group Displacement Law?*
- **Answer:** In α-emission, the parent element is displaced two groups to the left; in β-emission, it is displaced one group to the right.
**10. Disintegration Series:**
- *Define disintegration series.*
- **Answer:** A radioactive disintegration series is a sequence from a parent radioactive element to the stable end product, classified as 4n, (4n+1), (4n+2), and (4n+3).
**11. Half-life Period:**
- *What is the half-life period?*
- **Answer:** The half-life period is the time required for one-half of a radioactive isotope to decay (\(t_{1/2} = 0.693/\lambda\)).
**12. Rutherford:**
- *Define Rutherford.*
- **Answer:** Rutherford is a unit of radioactivity, where 1 Rutherford corresponds to 10^6 disintegrations per second.
**13. Radioactive Equilibrium:**
- *Explain radioactive equilibrium.*
- **Answer:** Radioactive equilibrium occurs when a daughter element disintegrates at the same rate it is formed from the parent element.
**14. Artificial Radioactivity:**
- *What is artificial radioactivity?*
- **Answer:** Artificial radioactivity is the result of artificial transmutation, leading to the formation of a radioactive nuclide.
**15. Alchemy:**
- *Define alchemy.*
- **Answer:** Alchemy is the process of transforming one element into another, and an individual involved in such experiments is called an alchemist.
**16. Spallation Reaction:**
- *What is a spallation reaction?*
- **Answer:** Spallation reaction involves high-speed projectiles chipping fragments from a heavy nucleus, leaving a smaller nucleus.
**17. Nuclear Fusion:**
- *Define nuclear fusion.*
- **Answer:** Nuclear fusion is a reaction where two lighter nuclei fuse to form a heavier nucleus.
**18. Nuclear Fission:**
- *Explain nuclear fission.*
- **Answer:** Nuclear fission is the artificial transmutation process where a heavy nucleus splits into two lighter nuclei.
**19. Projectile Capture Reactions:**
- *What are projectile capture reactions?*
- **Answer:** Projectile capture reactions involve the absorption of a bombarding particle with or without the emission of γ-radiations.
**20. Natural Transmutation:**
- *Define natural transmutation.*
- **Answer:** Natural transmutation is a process in which elements undergo transmutation on their own.
Long Answer Type Questions:
**1. Symbol, Mass, and Charges:**
- *What are the symbol, mass, and charges of electron, proton, and neutron?*
- **Answer:**
- Electron (\(e^-\)): Symbol - \(e^-\), Mass - \(9.11 \times 10^{-31}\) kg, Charge - \(-1.6 \times 10^{-19}\) C
- Proton (\(p^+\)): Symbol - \(p^+\), Mass - \(1.67 \times 10^{-27}\) kg, Charge - \(1.6 \times 10^{-19}\) C
- Neutron (\(n^0\)): Symbol - \(n^0\), Mass - \(1.67 \times 10^{-27}\) kg, Charge - 0
**2. Isobars and Isotones:**
- *What do you mean by Isobars and Isotones?*
- **Answer:**
- Isobars: Nuclides of different elements with the same mass number but different atomic numbers.
- Examples: \(^{40}_{18}Ar, ^{40}_{19}K, ^{40}_{20}Ca\)
- Isotones: Nuclides of different elements with the same number of neutrons but different atomic numbers.
- Examples: \(^3_1H, ^4_2He\)
**3. Nature, Penetrating Power, and Ionizing Power:**
-
*What are the nature, penetrating power, and ionizing power of α, β, and γ rays?*
- **Answer:**
- α-rays: Nature - Positive, Penetrating Power - Low, Ionizing Power - High
- β-rays: Nature - Negative, Penetrating Power - Moderate, Ionizing Power - Moderate
- γ-rays: Nature - Neutral, Penetrating Power - High, Ionizing Power - Low
**4. Binding Energy:**
- *What do you mean by ‘Binding energy’?*
- **Answer:** Binding energy is the energy that binds nucleons together in the nucleus, preventing it from splitting.
**5. Parent and End Products:**
- *What are the parent and end products of different disintegration series?*
- **Answer:**
- \(4n\) series: Uranium-238 (U-238) to Lead-206 (Pb-206)
- \((4n+1)\) series: Thorium-232 (Th-232) to Lead-208 (Pb-208)
- \((4n+2)\) series: Uranium-235 (U-235) to Lead-207 (Pb-207)
- \((4n+3)\) series: Uranium-233 (U-233) to Bismuth-209 (Bi-209)
**6. Curie and Becquerel:**
- *Define Curie and Becquerel.*
- **Answer:**
- Curie: Activity of 1 Curie corresponds to 37 × 10^10 disintegrations per second.
- Becquerel (SI unit): 1 Becquerel corresponds to 1 disintegration per second.
**7. Differences between Nuclear and Chemical Reactions:**
- *Give differences between Nuclear Reactions and Chemical Reactions.*
- **Answer:**
- *Nuclear Reactions:*
- Proceed by distribution of nuclear particles.
- One element may be converted into another.
- Rate of reaction is unaffected by external factors.
- *Chemical Reactions:*
- Proceed by the rearrangement of extranuclear electrons.
- No new element can be produced.
- Rate of reaction is influenced by external factors.
**8. Differences between Nuclear Fission and Fusion:**
- *What are the differences between nuclear fission and nuclear fusion?*
- **Answer:**
- *Nuclear Fission:*
- A bigger nucleus splits into smaller nuclei.
- Does not require high temperature.
- A chain reaction sets in.
- *Nuclear Fusion:*
- Larger nuclei fuse together to form a heavier nucleus.
- Extremely high temperature is required.
- It is not a chain reaction.
**9. Nature, Penetrating Power, and Ionizing Power of α, β, and γ rays:**
- *Explain the nature, penetrating power, and ionizing power of α, β, and γ rays.*
- **Answer:**
- α-rays: Positive nature, low penetrating power, high ionizing power.
- β-rays: Negative nature, moderate penetrating power, moderate ionizing power.
- γ-rays: Neutral nature, high penetrating power, low ionizing power.
