Question

Radioactive phosphorus-32 decays with a half-life of 14.0 days. A chemist obtains a fresh sample of phosphorus-32 and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 25% of the initial measured value. How many days does she have to perform the experiment

Answer 1

It will take 28 days to let the radioactivity fall below 25%.

What is Half Life ?

Half life can be described as the time required by the radioactive compound to reduce to half of the original value of concentration.

It is given that

Radioactive phosphorus-32 decays with a half-life of 14.0 days

25% of the initial measure at what time =?

For 50% decay the time needed is 14 days

for decay of the next 50%  of the amount left the time taken will be another 14 days

2nd half life = 25% decay of the substance = 28 days

Therefore it will take 28 days to let the radioactivity fall below 25%.

To know more about Half Life

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