What does the half-life formula t1/2 = 0.693/k relate to?

The half-life formula ( t_{1/2} = \frac{0.693}{k} ) specifically pertains to the time required for half of a radioactive substance to decay. In the context of radioactive decay, half-life is a crucial concept that indicates the duration it takes for a quantity of a radioactive material to reduce to half its initial amount. The constant ( k ) represents the decay constant, which is unique to each radioactive isotope and reflects the rate of decay.

This relationship is fundamental in various fields such as nuclear physics, chemistry, and environmental science, as it allows scientists to evaluate how long substances will remain radioactive or to date materials based on their remaining concentrations.

In contrast, the other options relate to different processes: doubling time refers to the time for a population or quantity to increase twofold, completion of a chemical reaction involves different kinetics and equilibrium considerations, and the travel time of light in a vacuum does not involve decay but rather the speed of light as a physical constant. Thus, the focus of the half-life formula is distinctly on decay processes.