Radioactivity

What class are you in?

• 11Y2A

• Other

Which type of radiation is the most ionising?

• Electromagnetic radiation
• Beta radiation
• Gamma radiation
• Alpha radiation

What does it mean to say that a substance is radioactive?

• Each atom in the substance has too many electrons; these electrons can escape.
• The substance will emit X-rays when heated.
• It contains unstable nuclei that become stable by emitting radiation.
• The nuclei of atoms in the substance will split up, giving out neutrons and energy.

How does a nuclear fission chain reaction continue?

• Released neutrons combine with each other.
• The energy released from each fission is enough to cause further fissions.
• Released neutrons cause further fissions.
• Released neutrons ionise other atoms.

Which type of radiation is the most penetrating?

• alpha
• beta
• gamma

Technetium-99m has a half-life of 6 hours. A hospital technician makes a batch of Tc-99m; it has an initial activity of 120 Bq. What is the activity 12 hours later?

• 30 Bq
• 7.5 Bq
• 10 Bq
• 60 Bq

In a uranium-powered nuclear reactor, what is the name for the part that slows down the fission neutrons?

• Control rod
• Coolant
• Fuel
• Moderator

What is the difference between radioactive contamination and irradiation of a material?

• Contamination involves ionising radiation, but irradiation does not.
• Irradiation makes the material radioactive, but contamination does not.
• Irradiation exposes a material to ionising radiation; contamination adds radioactive atoms to a material.
• Contamination and irradiation mean the same thing.

In Rutherford’s experiment, investigating the scattering of alpha particles from very thin gold foil, Geiger and Marsden observed that a few alpha particles were scattered by more than 90°. What conclusion could they make from this observation?

• The nucleus of an atom contains protons and neutrons.
• Most of the atom is empty space.
• The atom has a small positively charged nucleus holding most of the atom’s mass.
• Electrons move around inside the atom.

What will be the main product when strontium-90 undergoes beta decay?

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