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Worksheet: Radioactive Decay

Q1:

A radioactive sample initially contains mol of a radioactive material which has a half-life of 6.00 hours.

Approximately how many moles of the radioactive material remain after 6.00 h?

  • A mol
  • B mol
  • C mol
  • D mol
  • E mol

Approximately how many moles of the radioactive material remain after 12.00 h?

  • A mol
  • B mol
  • C mol
  • D mol
  • E mol

Approximately how many moles of the radioactive material remain after 36.00 h?

  • A mol
  • B mol
  • C mol
  • D mol
  • E mol

Q2:

A sample of radioactive material is obtained from a very old rock. A plot of the natural logarithm of the sample's activity versus time yields a slope value of s−1. What is the half-life of this material?


  • A years
  • B years
  • C years
  • D years
  • E years

Q3:

A piece of wood from an ancient Egyptian tomb is tested for its carbon-14 activity. It is found to have an activity per gram decay/ming. What is the age of the wood? Use a value of s−1 for the decay constant of carbon-14 and a value of for the relative abundance of carbon-14.