A2(g) BC(g)--> 2ABC Using the reaction above, if the rate of this reaction doubles when the concentration of A2 is doubled and the rate doubles when the concentration of OB is doubled. how much with the rate increase if both A2 and BC are doubled

That is a lot of moles that you have

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.