P6.1 Radioactive emissionsExam-style questions

Name ..................................................................... Class .................. Date .....................

1 A sample of gold atoms contains mostly gold-197, , and a few atoms of

gold-195, .

a Complete the table by calculating the number of particles present in gold-197 and gold-195.

Gold atom protons electrons neutrons

gold-197

gold-195

(2 marks)

b What name is given to atoms of an element such as gold-195 and gold-197?

(1 mark)

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P6.1 Radioactive emissionsExam-style questions

Name ..................................................................... Class .................. Date .....................

2 A scientist has three unknown sources of radiation. Describe how the scientist can determine which source emits alpha particles, beta particles, and gamma radiation. In your description, include some of the precautions the scientist must take to ensure that the investigation is conducted safely.

(6 marks)

3 The graph shows the change in activity over time for a radioactive source.

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P6.1 Radioactive emissionsExam-style questions

Name ..................................................................... Class .................. Date .....................

a Estimate the half-life of this substance.

(1 mark)

b Another radioactive substance has a half-life of 2.4 days and an activity of 5000 Bq.Estimate the activity after 9.6 days.

Activity: Bq (4 marks)

c A teacher uses a Geiger counter to measure the activity of a radioactive sample with a very long half-life.He calculates the mean activity over 5 minutes.Explain why the teacher did not hear one click per second from the Geiger counter.

(2 marks)

4 Equations can be used to represent nuclear decay.a i Complete the equation for the beta decay of carbon-14.

→ + (1 mark)

ii Explain where the beta particle comes from in beta decay.

(2 marks)

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P6.1 Radioactive emissionsExam-style questions

Name ..................................................................... Class .................. Date .....................

b An atom of neptunium-247, , decays by a series of alpha and beta decays.Calculate the mass and proton number of the element produced after the following decay series.

α → β− → α → α → β−

mass number: Protons: (5 marks)

c Mass is conserved in nuclear decay.Name one other property that is conserved. A ChargeB StabilityC Half-life D Energy

Your answer (1 mark)

5 Electrons can only occupy specified energy levels around the nucleus of an atom.

a An electron in the lowest energy level absorbs electromagnetic radiation and is temporarily excited to the next energy level.Describe what happens when the electron returns to its ground (unexcited) state.

(2 marks)

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P6.1 Radioactive emissionsExam-style questions

Name ..................................................................... Class .................. Date .....................

b The radiation that excited this electron had 1.6 × 10−18 J of energy.To completely remove the electron from the atom (ionisation) would take radiation with 25% more energy than this excitation radiation.Calculate the energy required to ionise the atom.

Energy: J

(3 marks)

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