All the disintegrations of a sample of an unknown nuclide weighing 4.6 × 10^-2 g were counted. In the first half-life of the sample, the total number of disintegrations counted was 4.3 × 10²⁰. What is the atomic weight of the unknown element? A) 32 amu B) 16 amu C) 8 amu D) 4 amu E) None of these choices are correct.

Question

Quizplus · Accepted Answer

The atomic weight of the unknown element is 32 amu. This is because the number of disintegrations in the first half-life is equal to the number of atoms in the sample, which is equal to the mass of the sample divided by the atomic weight.

All the Disintegrations of a Sample of an Unknown Nuclide