How many atoms of oxygen do 125 g of CO 2 contain? O 1.71 x 10 24
atoms
0 2.33 x 10 25
atoms
0 3.01 x 10 23 atoms
O
3.42 x 10 24 atoms
h

D. most models represent a real world object in a simpler way

The answer is solid copper 

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.