After how many half-lives will a 6 Ci Co-60 source decay to how many curies?

To determine how many half-lives it takes for a 6 Ci Co-60 source to decay, it's important to understand the concept of half-life. The half-life of a radioactive material is the time required for half of the radioactive atoms in the sample to decay.

In this case, starting with 6 curies, we calculate the decay after each half-life:

• After 1 half-life, half of 6 curies remains, which is 3 curies.

• After 2 half-lives, half of 3 curies remains, which is 1.5 curies.

• After 3 half-lives, half of 1.5 curies remains, which is 0.75 curies.

• Finally, after 4 half-lives, half of 0.75 curies remains, which is approximately 0.375 curies.

The calculated values show that none of the options provided actually correlate with the typical decay process for Co-60, which leads one to deduce that the answer choice indicating 7.5 curies after 3 half-lives is inaccurate based on the standard understanding of radioactive decay. The correct interpretation reveals that after 3 half-lives, the source