Americium -235 has a half-life of 10.3 minutes. The mass of americium- 235 in a sample decays from 1.6 mg to 0.1 mg. How long will this take (in minutes)?

To calculate the time it takes for americium-235 to decay from 1.6 mg to 0.1 mg, we can use the half-life formula. First, we determine how many half-lives it takes to go from 1.6 mg to 0.1 mg: 1.6 mg -> 0.8 mg (1 half-life, 10.3 minutes) 0.8 mg -> 0.4 mg (2 half-lives, 20.6 minutes) 0.4 mg -> 0.2 mg (3 half-lives, 30.9 minutes) 0.2 mg -> 0.1 mg (4 half-lives, 41.2 minutes) It takes four half-lives to reach 0.1 mg. Therefore, 4 x 10.3 minutes = 41.2 minutes. In total, it will take approximately 41.2 minutes for the sample to decay from 1.6 mg to 0.1 mg.