Worksheet: Measures of Radioactivity

In this worksheet, we will practice defining the becquerel, curie, gray, and sievert as units of decay activity, cell irradiation, and radiation dose.

Q1:

A sample of thorium-229 has a mass of 2.234 g. The half-life of this radioisotope is 7,340 years.

What is the activity of the sample in becquerels, to 3 significant figures?

  • A 1 . 7 6 × 1 0 Bq
  • B 4 . 0 3 × 1 0 Bq
  • C 7 . 6 3 × 1 0 Bq
  • D 1 . 0 5 × 1 0 Bq
  • E 4 . 2 2 × 1 0 Bq

What is the activity of the sample in curies, to 3 significant figures?

Q2:

A sample of cobalt-60 has a mass of 5.000 g. The half-life of this radioisotope is 5.26 years.

What is the activity of the sample in becquerels?

  • A 9 . 1 0 × 1 0 Bq
  • B 3 . 0 2 × 1 0 Bq
  • C 2 . 1 0 × 1 0 Bq
  • D 4 . 1 9 × 1 0 Bq
  • E 2 . 5 1 × 1 0 Bq

What is the activity of the sample in curies?

  • A 2 . 4 6 × 1 0 Ci
  • B 1 . 1 3 × 1 0 Ci
  • C 1 . 2 5 × 1 0 Ci
  • D 6 . 8 0 × 1 0 Ci
  • E 5 . 6 6 × 1 0 Ci

Q3:

A sample of tritium (hydrogen-3) has a mass of 1.000 mg. The half-life of this radioisotope is 12.32 years.

What is the activity of the sample in becquerels, to 3 significant figures?

  • A 1 . 1 8 × 1 0 Bq
  • B 9 . 4 0 × 1 0 Bq
  • C 3 . 5 8 × 1 0 Bq
  • D 3 . 9 2 × 1 0 Bq
  • E 1 . 5 7 × 1 0 Bq

What is the activity of the sample in curies, to 3 significant figures?

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