Radioactivity Alpha Beta Gamma Decay - UNSOLVED PRACTICE SET
Chapter: Nuclei | Topic: Radioactivity Alpha Beta Gamma Decay
RADIOACTIVITY ALPHA BETA GAMMA DECAY - UNSOLVED PRACTICE SET
Topic: Radioactivity Alpha Beta Gamma Decay
Multiple Choice Questions
Q1. Alpha particles are:
- High-energy electrons
- Helium nuclei (βHeβ΄)
- High-energy photons
- Neutrons
Q2. In alpha decay, the mass number of the parent nucleus:
- Increases by 4
- Decreases by 4
- Remains unchanged
- Increases by 2
Q3. Beta decay involves the emission of:
- A helium nucleus
- An electron or positron
- A high-energy photon
- A neutron
Q4. Gamma decay involves:
- Change in mass number and atomic number
- No change in mass number or atomic number
- Increase in atomic number by 1
- Decrease in atomic number by 2
Q5. The penetrating power of radiation is in the order
- Ξ± > Ξ² > Ξ³
- Ξ³ > Ξ² > Ξ±
- Ξ² > Ξ³ > Ξ±
- Ξ± > Ξ³ > Ξ²
Q6. In Ξ²β» decay, a neutron in the nucleus transforms into:
- A proton and an electron
- A proton, an electron, and an antineutrino
- A proton only
- A proton and a neutrino
Short Answer Questions
Q7. Compare alpha, beta, and gamma radiations in terms of:
(a) Nature
(b) Ionizing power
(c) Penetrating power
Q8. Write the general equation for alpha decay. How do the mass number and atomic number change?
Q9. What is the difference between Ξ²β» decay and Ξ²βΊ decay? Write the nuclear equations for each.
Q10. Why does gamma emission usually follow alpha or beta decay?
Q11. A radioactive nucleus undergoes alpha decay followed by two beta decays. What is the net change in mass number and atomic number?
Q12. Why are alpha particles deflected less than beta particles in a magnetic field, despite having greater charge?
Long Answer Questions
Q13. Describe alpha, beta, and gamma decay processes. Write the general nuclear equations for each and explain the changes in mass number and atomic number.
Q14. Explain the mechanism of Ξ²β» decay at the quark level. Why is a neutrino (or antineutrino) emitted in beta decay? Discuss the role of the weak nuclear force.
Q15. Compare the properties of alpha, beta, and gamma radiations in detail. Discuss their ionizing power, penetrating power, and effects on photographic plates and fluorescent screens.
Numerical & Application-based Problems
Q16. Thorium-232 undergoes alpha decay to form radium-228.
(a) Write the nuclear equation for this decay.
(b) Calculate the Q-value of this decay.
(c) Given that the mass of Th-232 is 232.038 u, Ra-228 is 228.031 u, and He-4 is 4.003 u, calculate the energy released in MeV.
Q17. Carbon-14 undergoes Ξ²β» decay to form nitrogen-14.
(a) Write the nuclear equation for this decay.
(b) The masses are: C-14 = 14.003 u, N-14 = 14.003 u (approximately equal). Explain why energy is still released in this decay.
(c) Calculate the maximum kinetic energy of the emitted electron if the actual masses are m(C-14) = 14.003242 u and m(N-14) = 14.003074 u.
Q18. In your school's physics exhibition, a student presents a project on radioactivity in everyday life.
(a) She explains that smoke detectors use americium-241, which undergoes alpha decay. Write the nuclear equation and explain why alpha particles are suitable for this application.
(b) The student discusses carbon-14 dating used to determine the age of archaeological samples from sites like Harappa and Mohenjo-daro. A wooden artifact has 25% of the carbon-14 activity compared to a fresh sample. Calculate the age of the artifact (half-life of C-14 = 5730 years).
(c) She mentions that potassium-40 in bananas is radioactive and undergoes beta decay. Write the nuclear equation and calculate the energy released per decay. (Mass of K-40 = 39.964 u, mass of Ca-40 = 39.963 u.)
(d) A classmate is worried about the radioactivity in bananas and refuses to eat them. Calculate how many bananas (each containing about 0.4 g of potassium, of which 0.012% is K-40) one would need to eat to receive a dose of 1 mSv, and use this to reassure your classmate.
(e) In India, nuclear medicine at hospitals like AIIMS uses technetium-99m for diagnostic imaging. Explain why this isotope (which emits gamma rays) is ideal for medical imaging, and why its half-life of 6 hours is advantageous.