Radioactivity 4 - Application questions

The half-life of this radioactive source is

• 4 minutes

• 4 hours

• 50

• 4 days

The time it takes for the activity of this radioactive source to drop to 25% of its original value is

• 4 minutes

• 8 minutes

• 2 minutes

• 6 minutes

A radioactive source has a half-life of 28 days. What proportion of the original radioactive source will be left after 84 days?

• 1/2

• 1/4

• 1/8

• 1/16

A radioactive source has a half-life of 45 minutes. What proportion of the original radioactive source will be left after 3 hours?

• 1/2

• 1/4

• 1/8

• 1/16

A radioactive source has 2 x 10⁹ atoms. After 2 half-lives how many of the original atoms will remain?

• 1 x 10⁹

• 5 x 10⁸

• 5 x 10⁹

• 5 x 10⁷

A radioactive source has 2 x 10⁹ atoms. After 2 half-lives how many of the original atoms will have decayed?

• 1.5 x 10⁹

• 5 x 10⁸

• 5 x 10⁹

• 1.5 x 10⁷

A radioactive source has 4 x 10¹² atoms and a half-life of 3 hours. How many of the original atoms will have decayed after 9 hours?

• 3.5 x 10¹²

• 5 x 10¹¹

• 3 x 10¹²

• 1 x 10¹²

A radioactive source has 4 x 10¹² atoms and a half-life of 3 hours. How many of the original atoms will remain after 9 hours?

• 3.5 x 10¹²

• 5 x 10¹¹

• 3 x 10¹²

• 1 x 10¹²

A radioactive source has a mass of 480g. What mass of sample will be left after 4 half-lives?

• 120g

• 30g

• 60g

• 240g

A radioactive source has 3000 atoms remaining after 2 half-lives. How many original atoms were in the sample.

• 6000 atoms

• 9000 atoms

• 12000 atoms

• 750 atoms