Radioactive Decay Activity and Half-Life Explained

The video tutorial explains the concepts of activity and half-life in radioactive materials. It describes how activity is the rate of decay measured in becquerels and how half-life is the time taken for the number of radioactive nuclei or activity to halve. The video uses graphs to illustrate decay processes and explains how to calculate half-life from these graphs. It also covers practical measurement of activity using a Geiger-Muller tube and provides an example problem to calculate remaining nuclei after a given time.

What is the primary reason we cannot predict when a single radioactive isotope will decay?

• The decay process depends on the isotope's size.

• The decay process is too slow to measure.

• The decay process is completely random.

• The decay process is influenced by external factors.

How is the activity of a radioactive sample measured?

• In sieverts, representing the radiation dose.

• In becquerels, representing the number of decays per second.

• In rads, representing the energy absorbed.

• In curies, representing the number of decays per minute.

What happens to the activity of a sample as the number of unstable particles decreases?

• The activity increases.

• The activity fluctuates randomly.

• The activity remains constant.

• The activity decreases.

What is the relationship between the number of radioactive nuclei and the activity of a sample?

• They are inversely proportional.

• They fluctuate independently.

• They are directly proportional.

• They are unrelated.

Why is the decay curve on a graph not a straight line?

• Because the decay rate is constant.

• Because the decay rate is unpredictable.

• Because the decay rate increases over time.

• Because the decay rate decreases over time.

If a sample has an initial activity of 600 becquerels, what will its activity be after one half-life?

• 300 becquerels

• 600 becquerels

• 150 becquerels

• 450 becquerels

What is the half-life of a sample if it takes 2 hours for its activity to drop from 600 to 300 becquerels?

• 1 hour

• 2 hours

• 4 hours

• 3 hours

What device is used to measure the activity of a radioactive sample in real life?

• A Geiger-Muller tube.

• A spectrometer.

• A dosimeter.

• A scintillation counter.

How many half-lives does it take for a sample to reduce from 3 million to 375,000 radioactive nuclei?

• Four half-lives

• Three half-lives

• Two half-lives

• One half-life

If a radioactive source has a half-life of 40 hours, how many nuclei remain after 120 hours if it started with 3 million?

• 1 million

• 375,000

• 750,000

• 1.5 million