Any molecule that contains only carbon, hydrogen, & oxygen atoms in a 1: 2: 1 ratio (e. g., c6h12o6) is a:

The answer to this is a carbohydrate compound. Carbohydrates have a general chemical formula of Cₓ(H₂O)ₓ. From the word itself, there is a ratio for every carbon atom that corresponds with the hydrate molecule or water. So, an empirical formula for a carbohydrate is CH₂O which coincides with the 1:2:1 ratio.

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.