How much of an 8 gram sample of 226 38 Ra will remain unchanged at the end of 3 half life periods?

What happens to isotopes that are unstable?

Asuspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. if one wishes to follow this process by monitoring the release of 14co2, at which positions in the glucose molecule would the 14c label need to be incorporated?

What must be in balance for temperatures to remain constant?