Final answer:
The concept of half-life is demonstrated by the regular halving of a radioactive substance's quantity over equal time intervals, which is indicative of an exponential decay pattern where the rate of decay is proportional to the current amount. The correct answer is C, as half-life refers to the time at which the quantity of a substance reduces to half its initial value.
Step-by-step explanation:
The question asks to identify how the given data demonstrates the meaning of half-life in the context of radioactivity. The correct answer is C. The quantity of the substance is halved at regular intervals. This is because half-life is a term used to describe the time required for half of the radioactive nuclei in a sample to undergo radioactive decay.
Different figures provided, such as Figure 22.24, Figure 31.19, and Figure 15.3.1, all illustrate that after each half-life, the number of radioactive nuclei decreases to half its previous amount. For example, if you start with 100 radioactive atoms, after one half-life you would have 50, after another half-life you would have 25, and so on. This process is known as exponential decay, and the rate of decay remains constant over time, meaning that the rate at which the substance decays is proportional to its current amount.