Final answer:
The mass of iodine-131 remaining after 24 days can be calculated using the concept of half-life.
Step-by-step explanation:
To calculate the mass of iodine-131 remaining after 24 days, we can use the concept of half-life. The half-life of iodine-131 is given as 8.1 days. Using this information, we can calculate the number of half-lives passed in 24 days by dividing 24 by 8.1, which gives us approximately 2.96. Since each half-life reduces the mass to half, after 2.96 half-lives, the mass remaining would be approximately 10g / (2^2.96) = 5g. Therefore, the correct answer is option b) 5g.