Answer:
A radioactive (unstable) phosphorus isotope is made to replace a nonradioactive isotope of phosphorus in the molecule
Explanation:
Phosphorus has both unstable (radioactive) and stable isotopes. In any compound that contains phosphorus, the phosphorus atom present may be either a stable isotope of phosphorus or an unstable isotope of phosphorus.
However, if the molecule contains a stable nonradioactive isotope of phosphorus, it is possible to convert this isotope in the molecule to the unstable radioactive isotope by carefully carrying out exchange reactions in which the phosphorus isotope replaces the nonradioactive isotope in the molecule.
This is usually done in order to create radioactive tracers which are used to study chemical reactions and biochemical processes.
The answer is natural selection
<u>Answer:</u>
<em>If no other changes occurred emigration would have a negative impact on the population density of a group of organisms.
</em>
<u>Explanation:</u>
<em>Emigration is the movement of a part of population out of an area into a new area. </em>It has a negative impact on the population of the old area and positive impact on the population of the new area.
Population density is the population per unit area that is population per square kilometer.
Thus population density will also be negatively affected by emigration. <em>Hence an area that previously was densely populated might become a sparsely populated area due to emigration. </em>