A radioactive sample falling from 80 g to 10 g in 6 hours has half-life 2 hours, and an alpha particle is a helium nucleus, so this IB sheet opens with an activity calculation and the alpha identity. E = mc² and a 1-day answer appear in the key.
Key Takeaways
80 g to 10 g in 6 hours gives half-life 2 hours (Q1).
An alpha particle is a helium nucleus (Q2).
Q4 records E = mc².
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.A radioactive sample decays from 80 g to 10 g in 6 hours. The half-life is
(a) 1 h(b) 2 h(c) 3 h(d) 4 h
2.An alpha particle is
(a) a helium nucleus(b) an electron(c) a photon(d) a neutron
3.In beta-minus decay, a neutron in the nucleus changes into
(a) a proton, an electron and an antineutrino(b) a proton and a neutrino(c) an electron and a neutrino(d) two protons
4.The energy released in a nuclear reaction is calculated using
(a) E = ½mv²(b) E = mc²(c) E = hf(d) E = qV
5.A radioactive isotope has a decay constant of 0.693 day⁻¹. Using T½ = ln 2 ÷ λ, its half-life is
(a) 1 day(b) 0.693 day(c) 2 days(d) 1.44 days
6.The mass number of a nucleus is equal to
(a) the number of protons(b) the number of neutrons(c) the total number of protons and neutrons(d) the number of electrons
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Define the half-life of a radioactive isotope.
8.State the properties of alpha radiation.
9.State the properties of gamma radiation.
10.Explain what is meant by the mass defect of a nucleus.
11.State the relationship between the mass defect and the binding energy of a nucleus.
12.Write the symbol for a beta-minus particle.
13.State what is meant by radioactive decay.
14.Explain why alpha particles are less penetrating than beta particles.
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A sample has an initial mass of 120 g and a half-life of 4 days. Using N = N₀ × (½)ⁿ with n = t ÷ T, calculate the mass remaining after 12 days.
16.Using A = λN, calculate the initial activity of a sample containing 10²⁰ radioactive nuclei with a decay constant of 3.0 × 10⁻² s⁻¹.
17.The mass defect of a nucleus is 0.030 u. Using the conversion 1 u = 931 MeV, calculate the binding energy of the nucleus.
18.Using the factor (½)ⁿ, calculate the fraction of a radioactive sample that remains after 5 half-lives.
19.Using E = mc² with c = 3 × 10⁸ m/s, calculate the energy released when a nucleus loses 3.2 × 10⁻²⁷ kg of mass.
20.A 5 g sample has a half-life of 6 hours. Using N = N₀ × (½)ⁿ with n = t ÷ T, calculate the mass remaining after 18 hours.
Answer Key
1. b) 2 h
2. a) a helium nucleus
3. a) a proton, an electron and an antineutrino
4. b) E = mc²
5. a) 1 day
6. c) the total number of protons and neutrons
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is the half-life of a sample falling from 80 g to 10 g in 6 hours?
2 hours, option (b) in this worksheet (Q1).
What is an alpha particle?
A helium nucleus, option (a) in this worksheet (Q2).
What is the mass–energy relation?
E = mc², option (b) in this worksheet (Q4).
Stuck on a similar problem? Clear your next doubt instantly with the Doubt Solver.
Browse more free worksheets for IB Year 13.