The FDA requires retention of investigational drug study records for The answer is C. At least two years after the investigational drug's approval by the FDA
An investigator shall retain records needed to be preserved under this part for a period of two years following the date a marketing operation is approved for the drug for the explanation for which it is being investigated
Half life formula
The number of unstable nuclei remaining after time t can be determined according to this equation:
N(t) = N(0) * 0.5^(t/T)
where:
N(t) is the remaining quantity of a substance after time t has elapsed.
N(0) is the initial quantity of this substance.
T is the half-life.
It is also possible to determine the remaining quantity of a substance using a few other parameters:
N(t) = N(0) * e^(-t/τ)
N(t) = N(0) * e^(-λt)
τ is the mean lifetime - the average amount of time a nucleus remains intact.
λ is the decay constant (rate of decay).
All three of the parameters characterizing a substance's radioactivity are related in the following way:
T = ln(2)/λ = ln(2)*τ
How to calculate the half life
Determine the initial amount of a substance. For example, N(0) = 2.5 kg.
Determine the final amount of a substance - for instance, N(t) = 2.1 kg.
Measure how long it took for that amount of material to decay. In our experiment, we observed that it took 5 minutes.
Input these values into our half life calculator. It will compute a result for you instantaneously - in this case, the half life is equal to 19.88 minutes.
If you are not certain that our calculator returned the correct result, you can always check it using the half life formula.
<span>These organisms obtain energy and carbon from the physical environment and use it to produce their food. They make sugars and other compounds using sunlight as a source of energy and carbon dioxide as a carbon source. The evolutionary advantages for these organisms are the periodic renewal of atmospheric O2 for all living beings. The production of organic matter and food webs of any ecosystem. Without them, there is an extinction of all living organisms due to the non-renewal of atmospheric O2 and the excessive accumulation of CO2 in the atmosphere.</span>
Solutions that have more H+ ions are acids.
