How many atoms are in a 121.4 gram sample of Aluminum (Al)? a
2.71 X 10 ^ 24 atoms
b
4.5 atoms
c
1.97 X 10 ^ 27 atoms
d
5.44 X 10 ^ -21 atoms

The correct answer is c

Ibelieve the answer is d

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.