Find the number of moles of argon in 452 g of argon

No. of moles = given mass/atomic mass

= 452/40

= 11.3.

Thus, there are 11.3 moles

Nó of moles =given mass/molar mass
no of moles=452/39.9
therefore no of moles=11.3moles

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.