Chemistry Test Nuclear Chemistry 1 — Questions and Answers
Question 1: What particle is emitted during alpha decay?
- Electron (β⁻)
- Positron (β⁺)
- Helium-4 nucleus (²₂He) (Correct answer)
- High-energy photon
Correct answer: Helium-4 nucleus (²₂He)
Alpha decay emits an alpha particle, which is identical to a helium-4 nucleus (2 protons and 2 neutrons, ²₄He).
Question 2: During beta-minus (β⁻) decay, which particle is emitted from the nucleus?
- Proton
- Neutron
- Electron (Correct answer)
- Alpha particle
Correct answer: Electron
In beta-minus decay, a neutron converts to a proton and emits an electron (β⁻ particle) and an antineutrino.
Question 3: What is the half-life of a radioactive isotope?
- Time for half the atoms to gain energy
- Time for the activity to double
- Time for half the radioactive atoms to decay (Correct answer)
- Half the total lifetime of the nucleus
Correct answer: Time for half the radioactive atoms to decay
The half-life is the time required for exactly half of the radioactive nuclei in a sample to undergo decay.
Question 4: Which type of radiation has the greatest penetrating power?
- Alpha (α)
- Beta (β)
- Gamma (γ) (Correct answer)
- All have equal penetrating power
Correct answer: Gamma (γ)
Gamma radiation consists of high-energy photons with no mass or charge, giving it the greatest penetrating power — requiring lead or thick concrete to shield.
Question 5: What does the mass number (A) of a nucleus represent?
- Number of protons only
- Number of neutrons only
- Total number of protons and neutrons (Correct answer)
- Atomic weight in grams
Correct answer: Total number of protons and neutrons
The mass number (A) is the total count of nucleons (protons + neutrons) in the nucleus of an atom.
Question 6: What is nuclear fission?
- Combining two light nuclei into a heavier one
- Splitting a heavy nucleus into smaller fragments releasing energy (Correct answer)
- Emitting an alpha particle from a nucleus
- Converting a proton to a neutron
Correct answer: Splitting a heavy nucleus into smaller fragments releasing energy
Nuclear fission is the splitting of a heavy nucleus (e.g., U-235) into smaller nuclei, releasing a large amount of energy and additional neutrons.
Chemistry Test Nuclear Chemistry 1
What particle is emitted during alpha decay?