It is a presumptive test for cocaine.
Answer:

Explanation:
A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.
The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.
For a radioactive isotope, the amount of substance left after a certain time t is:
(1)
where
is the mass of the substance at time t = 0
m(t) is the mass of the substance at time t
is the half-life of the isotope
In this problem, the isotope is uranium-235, which has a half-life of

We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that

Substituting into (1) and solving for t, we can find how much time has passed:

During the winter solstices, we experience the longest day and the shortest night while during the summer solstices the sun is at its highest point in the sky.
<h3>What is the Solsticest?</h3>
The Solstices is the season that occurs at the moment the earth's tilt toward or from the sun is at a maximum. There are two seasons of Solstices which include the following:
- The winter solstices: This occurs when the sun is directly over the Tropic of Capricorn causing us to have the shortest day and longest night of the year.
- The summer solstices: The sun is at its highest elevations.
Learn more about solstices here:
brainly.com/question/25859051
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This process is called metabolites!