Base your answer on the information below. The radioisotope uranium-238 occurs naturally in Earth's crust. The disintegration of this radioisotope is the first in a series of spontaneous decays. The sixth decay in this series produces the radioisotope radon-222. The decay of radon-222 produces the radioisotope polonium-218 that has a half- life of 3.04 minutes. Eventually, the stable isotope lead-206 is produced by the alpha decay of an unstable nuclide. Determine the original mass of a sample of Po-218, if 1.50 milligram of the sample remains unchanged after 9.12 minutes

12 mmilligrams of Po-218 was the mass of the original starting material

Explanation:

The half-life of a radioactive material is the time taken for half the amount ofnthe original material present in a radioactive material to decay or disintegrate.

After each half-life, half the original material present at the start remains.

For the radioactive polonium-218 having a half-life of 3.04 minutes, it means that if 1 g is the starting material, after 3.04 minutes, 1/2 g will be remaining; after, 6.08 minutes 1/2 of 1/2 which is 1/4 of the starting material will be remaining; and after 9.12 minutes, 1/2 of 1/4 = 1/8 g will be remaining.

From the question, number of half-lives undergone after 9.12 minutes = 9.12/3.04 = 3 half-lives.

After 3 half-lives, 1/8 of the original material is remaining.

1/8 = 1.50 mg

The original mass of the sample at the start = 1.50 mg × 8 = 12 mg

Therefore, 12 milligrams of Po-218 was the mass of the original starting material.

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons