Radioactivity New2

A radioactive nucleus emits either an α-particle or a β-particle.

What are the products of these two types of radioactive emission?

• A

• B

• C

• D

A reading is taken every 10 minutes of the number of emissions per second from a radioactivesource. The table shows the readings.

What is the half-life of the source?

• 10 min

• 20 min

• 40 min

• 60 min

The graph shows how the decay rate of a radioactive source changes with time.

What will be the activity at 8 days?

• 0 decays / s

• 125 decays / s

• 250 decays / s

• 500 decays / s

Radioactive materials should be handled carefully.

Which safety precaution does not reduce the risk to people using a radioactive material?

• keeping the material a long distance from people

• keeping the material at a low temperature

• using lead screening between the material and people

• using the material for only a short time

A sample of a radioactive isotope has an initial rate of emission of 128 counts per minute and ahalf-life of 4 days.

How long will it take for the rate of emission to fall to 32 counts per minute?

• 2 days

• 4 days

• 8 days

• 12 days

A scientist carries out an experiment using a sealed source which emits β-particles. The range of the β-particles in the air is about 30 cm.

Which precaution is the most effective to protect the scientist from the radiation?

• handling the source with long tongs

• keeping the temperature of the source low

• opening all windows in the laboratory

• washing his hands before leaving the laboratory

Which row describes the nature of α-particles and of γ-rays?

• A

• B

• C

• D

The diagram shows the paths of three different types of radiation, X, Y and Z.

• A

• B

• C

• D

A powder contains 400 mg of a radioactive isotope that emits α-particles.

The half-life of the isotope is 5 days.

What mass of this isotope remains after 10 days?

• 0 mg

• 40 mg

• 100 mg

• 200 mg

Which row gives the properties of the radiation from radioactive materials?

• A

• B

• C

• D