Chemistry is the branch of science that deals with the identification of the substances of which matter is composed the investigation of their properties and the ways in which they interact, combine, and change and the use of these processes to form new substances.
Answer:

Explanation:
The question will be easier to solve if we interpret it as, " How long will it take until one-fourth of a sample of the element remains,?"
The half-life of the element is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:


Based on the standards of units conversion, to convert from micrometer to meter, we multiply by 10^-6.
Since we there is a square (10^2) to consider, then to convert from micrometer squared to meter squared, we will multiply by (10^-6)^2 as follows:
1.5 <span>μm2 = 1.5 x (10^-6)^2 = 1.5 x 10^-12 meter sqaures</span>