Radioactivity - alpha, beta and gamma rays; the decay law — practice questions

Question 1 · difficulty L1 · recall

Alpha radiation consists of

• A. electrons only
• B. high-energy photons
• C. helium nuclei
• D. neutrons only

Question 2 · difficulty L1 · understanding

Beta-minus decay emits

• A. a helium nucleus
• B. a gamma photon only
• C. a proton as the beta particle
• D. an electron along with an antineutrino in the full process

Question 3 · difficulty L2 · understanding

Gamma radiation consists of

• A. high-energy electromagnetic photons
• B. helium nuclei
• C. electrons only
• D. protons only

Question 4 · difficulty L2 · application

Radioactive decay law is

• A. N=N0(1+λt)
• B. N=N0 e^(-λt)
• C. N=N0 e^(+λt)
• D. N=λt only

Question 5 · difficulty L3 · application

Half-life is related to decay constant by

• A. T1/2=λ ln2
• B. T1/2=1/(2λ)
• C. T1/2=ln2/λ
• D. T1/2=λ

Question 6 · difficulty L3 · application

After three half-lives, the undecayed fraction is

• A. 1/3
• B. 1/6
• C. 1/9
• D. 1/8

Question 7 · difficulty L4 · analysis

Activity A of a radioactive sample is

• A. A=λN
• B. A=N/λ
• C. A=λ/N
• D. A=N0-N only

Question 8 · difficulty L4 · analysis

If a sample's half-life is 10 days, after 20 days its activity is

• A. one-half
• B. one-fourth of the initial activity
• C. one-eighth
• D. unchanged

Question 9 · difficulty L5 · analysis

Which radiation is generally most penetrating among alpha, beta and gamma?

• A. Alpha
• B. Beta
• C. Gamma
• D. All exactly equal

Question 10 · difficulty L5 · analysis

A radioactive nucleus emits an alpha particle. Its mass number and atomic number change by

• A. A→A and Z→Z+1
• B. A→A-1 and Z→Z
• C. A→A-4 and Z→Z+2
• D. A→A-4 and Z→Z-2