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Worksheet: Measures of Radioactivity

Q1:

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 Bq?

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

What is the activity of the sample in Ci?

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

Q2:

A sample of thorium-229 has a mass of 2.234 g. The half-life of this radioisotope is 7 3 4 0 years.

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

  • A 1 . 0 5 × 1 0 1 2 Bq
  • B 4 . 2 2 × 1 0 1 1 Bq
  • C 7 . 6 3 × 1 0 9 Bq
  • D 1 . 7 6 × 1 0 1 0 Bq
  • E 4 . 0 3 × 1 0 1 2 Bq

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

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 Bq, to 3 significant figures?

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

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