How can air pollution affect plants? A. Air pollution can block sunlight from reaching plants.

B. Air pollution can affect the water plants need.

C. Air pollution absorbs carbon dioxide.

D. Air pollution can change normal temperatures of a region.

B. nuclear reactions could first occur.

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.