What is the total mass of rn 222 remaining in an original 160 mg sample of rn 222 after 19.1 days?

To determine the remaining mass of Rn-222 after 19.1 days, we need to use its half-life, which is approximately 3.8 days. After 19.1 days, which is about 5 half-lives (19.1 days / 3.8 days), the remaining mass can be calculated using the formula: remaining mass = initial mass × (1/2)^(number of half-lives). Thus, the remaining mass of Rn-222 is 160 mg × (1/2)^5, which equals approximately 5 mg.