5

• Carbon-14 and carbon-12 are isotopes of carbon. Compare the structure of an atom of carbon-14 with the structure of an atom of carbon-12.

  Same number of protons and electrons

  Different number of neutrons
• Carbon-14 is a radioactive isotope. Carbon-14 has a half-life of 5700 years.

  What does 'a half-life of 5700 years' mean?

  The time it takes for the count rate of a radioactive sample to halve is 5700 years.
• A sample of fluorine-17 has an activity that is one quarter of its original activity. Calculate the age of the sample of fluorine-17 if its half life is 64.37 seconds.

  128.74s.
• Explain which isotope would cause the biggest risk to a person's health based only on the half-life of each isotope.

  Nitrogen-18

  Greatest activity, greatest amount of radiation absorbed per second
• Describe the difference between irradiation and contamination.

  Irradiation is exposure to radiation, contamination is the presence of radioactive material on/within something.
• Give two health risks to a person working close to a nuclear radiation source.

  Radiation poisoning or cancer.
• Workers in nuclear power stations are monitored to check the radiation they emit. A worker stands 1 cm away from a radiation detector. The amount of radiation the worker emits is recorded.

  Explain why the worker needs to stand close to the radiation detector.

  Alpha radiation has a very short range in air.
• daily dose caused by working in a nuclear power station = 0.00050 mSv

  hourly dose from cosmic rays to a pilot while flying = 0.0030 mSv

  Calculate the number of days it takes for a nuclear power station worker to receive the same dose as a pilot flying for 24 hours.

  pilot's dose in 24 hours = 0.072

  number of days = 0.072 / 0.0005

  number of days = 144