Nuclear Physics Quiz

Grade 11 · Science · Quiz

Test your knowledge of radioactive decay, nuclear reactions, binding energy, and fission versus fusion.

Questions

1. What particle is emitted in beta-minus decay?

   1. Proton
   2. Neutron
   3. Electron
   4. Alpha particle
   Show answer

   Answer: Electron

   Beta-minus decay: a neutron converts to a proton, emitting an electron (beta particle) and an antineutrino.

2. Carbon-14 has a half-life of 5730 years. A sample currently has 25% of its original C-14. How old is the sample?

   1. 5730 years
   2. 11460 years
   3. 17190 years
   4. 22920 years
   Show answer

   Answer: 11460 years

   25% = (1/2)² means 2 half-lives have passed. 2 × 5730 = 11,460 years.

3. Which nucleus has the highest binding energy per nucleon, making it the most stable?

   1. Hydrogen-1
   2. Helium-4
   3. Iron-56
   4. Uranium-238
   Show answer

   Answer: Iron-56

   Iron-56 has the highest binding energy per nucleon (~8.8 MeV), making it the most stable nucleus. Elements lighter or heavier release energy when fused or fissioned, respectively, toward iron.

4. In nuclear fission of U-235, a neutron is absorbed and the nucleus splits. This reaction releases energy primarily because:

   1. Electrons are ionized from the atom
   2. The products have greater mass than the reactants
   3. The products have less mass than the reactants, and the mass defect is released as energy
   4. The strong force is eliminated
   Show answer

   Answer: The products have less mass than the reactants, and the mass defect is released as energy

   The total mass of fission products is slightly less than the original nucleus + neutron. This mass defect Δm is converted to energy via E = Δmc².

5. Which type of radiation is stopped by a thin sheet of paper?

   1. Gamma
   2. Beta
   3. Alpha
   4. Neutron
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   Answer: Alpha

   Alpha particles (helium-4 nuclei) are heavy and doubly charged; they lose energy quickly and are stopped by a thin sheet of paper or a few centimeters of air.

6. What is conserved in all nuclear reactions?

   1. Mass only
   2. Charge only
   3. Both mass number and atomic number
   4. Neither mass nor charge
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   Answer: Both mass number and atomic number

   Nuclear reactions conserve both mass number (A) and atomic number (Z) — these are conservation laws for nucleon number and charge.

7. In beta-plus (positron) decay, the atomic number of the daughter nucleus increases by one.

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   Answer: False

   In beta-plus (positron) decay, a proton converts to a neutron, so Z decreases by 1 (not increases). The daughter element is one position lower on the periodic table.

8. The force responsible for holding nucleons together in the nucleus is called the _____ nuclear force.

   Show answer

   Answer: strong

   The strong nuclear force (or strong interaction) binds protons and neutrons together in the nucleus, overcoming electrostatic repulsion at ranges of about 10⁻¹⁵ m.

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