Obtain and Communicate Information 1. SEP Obtain Scientific Information Conduct research to learn about the history of atomic models and the scientists who developed the models. Identify any experimental evidence and reasoning that supported each model. I​

The answer to the question is d

Depends on the speed of the car.

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.