  Q1. Which of the following best describes the decay constant for a radioisotope?

 A The reciprocal of the half-life of the radioisotope. B The rate of decay of the radioisotope. C The constant of proportionality which links half-life to the rate of decay of nuclei. D The constant of proportionality which links rate of decay to the number of undecayed nuclei.

Q2. After 64 days the activity of a radioactive nuclide has fallen to one sixteenth of its original value. Calculate the half-life of the radioactive nuclide.

 A 2 days. B 4 days. C 8 days. D 16 days.

Q3. Radioactive decay is described as being spontaneous. In this context spontaneous means:

 A nothing can influence the decay B the decay is random C the decay can be predicted D the decay is exponential

Q4. The ionising properties of radiations determine their penetration power.

 A α-particles are not very ionising so they are easily stopped by a thin sheet of paper. B α-particles are very ionising so they only travel a few centimetres in air C γ-radiation can easily penetrate a sheet of card because it is very ionising D γ-radiation is not very penetrating because it is very ionising

Q5. Protactinium has a half life of 70s. A sample of protactinium is prepared and monitored over a period of time. Which of the following statements is correct?

 A After 140s the activity will be zero. B The activity of the sample will have dropped to 25% of its initial value after 140s. C The activity of the sample will have dropped to 12.5% of its initial value after 280s. D The activity of the protactinium will never become zero.

Q6. Which of the following does not contribute to background radiation?

 A Mobile (or cell) phones B Rocks C Decaying biological matter D Living creatures

Q7. A radioactive source is placed 2.0 cm from a detector. The count rate decreases slightly if a sheet of paper is inserted between the source and the detector. It is reduced to background radiation level if the sheet of paper is replaced by a 1.0 cm thick sheet of aluminium.

Deduce what forms of radiation the source emits:

Q8. Before carrying out a radioactivity experiment it is necessary to carry out a background radiation count (so that you can calculate the background count rate). The value of that count is not affected by:

 A The location of the experiment. B The ambient temperature. C The time interval used for the count. D The type of detector used.

Q9. Within a school laboratory you should always handle radioactive sources with long handled tongs and keep the time of use to a minimum. Choose from the choices below which form of radiation this safety advice most applies to, and for which reason.

 Type of Radiation Reason A α-particles It is the most ionising B α-particles It is the most massive C β-particles It can penetrate up to a metre of air D β-particles It can penetrate the skin and enter the body

Q10. Some rocks contain lead as a product of radioactive decay. Via one such decay chain a fixed quantity of polonium decays to a stable isotope of lead.

Which sketch graph best shows the number of lead atoms (N) in the sample as time progresses? Q11. The sodium isotope is a radioactive isotope that can be produced by bombarding the aluminium isotope with neutrons.

Which line, A to D, in the table below correctly represents the production of from the aluminium isotope and its subsequent decay?

 Production Decay A +   +    + + B +   +    + + C +   +    + + D +   +    + + Q12. Artificial radioactive nuclides are manufactured by placing naturally-occurring nuclides in a nuclear reactor. They are made radioactive in the reactor as a consequence of bombardment by:

 A gamma rays B β particles. C protons D neutrons. 