IB DP Physics Questions

7.1 Discrete Energy & Radioactivity

Question 1

Which of the following best describes the Bohr model of the atom?

A. Electrons move in fixed orbits around the nucleus.

B. Electrons move randomly within a cloud around the nucleus.

C. Electrons and protons are evenly distributed throughout the atom.

D. Electrons can be found anywhere within the atom without a fixed path.

Question 2

During which type of radioactive decay is a positron emitted?

A. Alpha decay

B. Beta-minus decay

C. Beta-plus decay

D. Gamma decay

Question 3

Which of the following has the greatest penetrating ability?

A. Alpha particles

B. Beta-minus particles

C. Gamma rays

D. Neutrons

Question 4

The half-life of a radioactive substance is 8 years. How many years will it take for the activity of the substance to reduce to 1/8 of its original value?

A. 8 years

B. 16 years

C. 24 years

D. 32 years

Question 5

Which of the following is NOT a beneficial use of radioactivity?

A. Powering spacecraft

B. Sterilising medical equipment

C. Enhancing plant growth

D. Treating cancer

Question 6

a) Describe the Bohr model of the atom and highlight its main limitations. [3]

b) An electron in a hydrogen atom transitions from the n=3 energy level to the n=2 energy level. Calculate the energy of the emitted photon using the formula: E = 13.6(1/nf^2 - 1/ni^2) eV. [3]

Question 7

a) Differentiate between alpha, beta-minus, and gamma decay in terms of their properties and penetration abilities. [4]

b) A radioactive sample emits beta-minus particles. What change occurs in the nucleus of the atom during this decay? [2]

Question 8

a) Define the term 'half-life' in the context of radioactive decay. [2]

b) A radioactive substance has a half-life of 5 years. If you start with 100g of the substance, how much of it will remain undecayed after 15 years? [3]

Question 9

a) Explain the concept of photon emission and absorption in relation to electron transitions in an atom. [3]

b) Using the formula E = 13.6(1/nf^2 - 1/ni^2) eV, calculate the energy difference when an electron transitions from the n=4 energy level to the n=2 energy level in a hydrogen atom. [3]

c) How does this energy difference relate to the energy of the emitted or absorbed photon? [2]

Question 10

a) Describe the three types of radioactive decay: alpha, beta, and gamma. [3]

b) A certain radioactive element undergoes beta-plus decay. What changes occur in its nucleus? [3]

c) Why is it essential to use protective measures when working with radioactive materials? [2]