Atomic Structure

When food is eaten, some of the radiation the food emits is detectable outside the body. Which type of radiation would not be detectable outside the body?

• alpha
• beta
• gamma

The activity of a sample of potassium-40 is measured 3 times. These are the measurements- 4906Bq, 4956Bq, 4889Bq. Which one of the statements explains why the readings are different?

• Radioactive decay is constant
• Radioactive decay is hazardous
• Radioactive decay is random.

A nucleus is much smaller than an atom. Approximately how many times smaller is a nucleus than an atom?

• 100
• 1000
• 10000
• 100000

Which kind of radiation is stopped by a piece of paper?

• alpha
• beta
• gamma

Which type of radiation is blocked by a thin layer of aluminium?

• alpha
• beta
• gamma

Which type of radiation is stopped by a thick layer of lead?

• alpha
• beta
• gamma

Which safety precautions should be used when handling radioactive sources?

• wear safety glasses
• keep the source outside the box for as little time as possible
• wear a lab coat
• handle the source with tongs
• hold the source away from the body and don't point it at people

The teacher wears polyethene gloves as a safety precaution when handling radioactive materials. The polyethene gloves do not stop the teachers hands from being irradiated. Why does the teacher wear polythene gloves?

• To prevent contact with germs
• To stop any radioactive material coming into contact with the skin
• To look scientific

In a nuclear reactor a chain reaction occurs which causes neutrons to be released. The control rods absorb neutrons. The control rods can be moved up and down. How is the energy released by the chain reactions is affected by lifting the control rods?

• The energy released decreases
• The energy released increases
• The energy released stays the same

A helium nucleus has two protons and two neutrons. What charge does it have?

• -2
• 0
• +2
• +4
• -4