Types of radiation, background radiation and detection: Practice Questions

In the process of \(\beta^-\text{ (beta minus)}\) decay, which change occurs within the nucleus of an atom?

A sample of a radioactive isotope contains \(N_0\) nuclei. After a certain time, the activity has declined to \(\frac{1}{16}\) of its original value. How many half-lives have passed, and what is the net decline in activity expressed as a ratio?

A radioactive isotope has an initial activity of \(800\text{ Bq}\). If its half-life is \(10\text{ minutes}\), what will be its activity after \(30\text{ minutes}\)?

In a nuclear reactor, the chain reaction is controlled to ensure a steady release of energy. Which of the following correctly describes the roles of the moderator and the control rods in this process?

A radioactive source has an initial activity of \(1200\text{ Bq}\). After a period of \(24\text{ hours}\), the activity has decreased to \(150\text{ Bq}\). Calculate the net decline in activity expressed as a ratio of the final activity to the initial activity, and determine the half-life of the isotope.

A radioactive sample has an initial activity of \( 800\text{ Bq} \). Calculate the final activity of the sample after a period of time equal to exactly three half-lives.

A student uses a Geiger-Müller tube to measure the activity of a radioactive isotope over several days. The initial count rate, after subtracting background radiation, is 800 counts per minute (cpm). After 12 days, the count rate has fallen to 100 cpm.