Question

Half-life is defined as:

A. The half way to the expiration date for the drug
B. The time required for the amount of drug in the body to decrease by 50%
C. The dose of drug that is effective in 50% of patients
D. One half the volume of distribution

Answer 1

The half-life is the time it takes for the concentration of a substance to decrease to half its initial value, often used in the context of radioactive decay or drug metabolism.

Step-by-step explanation:

The half-life is defined as the period of time it takes for the concentration of a reactant to decrease to one-half its initial value. This concept is often used in the context of radioactivity, where it refers to the time required for half of a radioactive substance to decay. The half-life of a reaction can vary depending on the substance's rate constant, and it applies similarly to processes such as drug metabolism in the body, where it describes the time needed for the amount of drug in the body to decrease by 50%.

For example, if a certain radioisotope has a half-life of 200 years, this means that it takes 200 years for 50% of the initial amount of the radioisotope to decay. After another 200 years (a total of 400 years), only 25% would remain because half of the remaining 50% would have decayed. This process continues, with the quantity of the substance halving at each interval equal to its half-life.