How long does it take for the radioactivity to drop?

From the start of timing it takes two days for the activity to halve from 80 Bq down to 40 Bq. It takes another two days for the activity to halve again, this time from 40 Bq to 20 Bq. Note that this second two days does not see the activity drop to zero, only that it halves again.

How long does it take for half of a radioactive sample to decay?

Radioactive Decay – Measuring the Age of the Solar System The half-life of a radioactive element is the amount of time it takes for half of the atoms in a sample to decay from an unstable state to a stable one. C (carbon) decays into 12C (carbon), with a half-life of 5,730 years.

Why does the activity of a radioactive sample reduce with time?

Radioactive decay causes a reduction in the number of unstable nuclei in a sample. In turn, this reduces the count rate measured by a detector such as a Geiger-Muller tube . Another way to define the half-life of a radioactive isotope is the time taken for count rate from a sample to decrease by a half.

Can you speed up radioactive decay?

The rate of this kind of decay depends on the chance of an electron straying into the nucleus and getting absorbed. So increasing the density of electrons surrounding the atomic nucleus can speed up the decay.

How long does it take for 90\% of a given quantity of the radioactive element cobalt 60 to decay given that its half-life is 5.3 years?

1 For cobalt-60, which has a half-life of 5.27 years, 50\% remains after 5.27 years (one half-life), 25\% remains after 10.54 years (two half-lives), 12.5\% remains after 15.81 years (three half-lives), and so on.

How long does it take for 90\% of a given quantity of the radioactive element cobalt-60 to decay given that its half-life is 5.3 years?

How much of a radioactive sample would be left after 5 half-lives?

97\%
Thus a first-order chemical reaction is 97\% complete after 5 half-lives and 100\% complete after 10 half-lives.