posted by Jazmin .
a radioisotope is called a tracer when it is used to
1 kill bacteria
2 kill cancerous cells
determine the age of animal skeletal remains
4 determine the path of an element in an organism
is it 3 ?
A tracer element is an element added to an experiment. Then one can look for that tracer element (radioisotopes are easy to use since we can count them) and we can see where the tracer shows up; hence, we can know the path of the reaction.