Final answer:
The half-life of a radioactive substance is the time it takes for half of the substance to decay.
Step-by-step explanation:
The half-life of a radioactive substance is the time it takes for half of the substance to decay. In this case, a radioactive substance decays from 600 g to 200 g in 10 days. To determine the half-life, we can use the formula:
Final amount = Initial amount * (1/2)^(n)
where n is the number of half-lives that have passed. In this case, the initial amount is 600 g, the final amount is 200 g, and the number of half-lives is 10 / t (t being the half-life).