Why is it useful for scientists to develop models for the structure of atoms? A. Atoms are too small to study directly.
B. Atoms move too quickly to see.
C. Looking at atoms directly can be harmful.
D. Atoms are too far away to study.

How can a scientist assess whether a pure niobium (nb) sample is responsible for contaminating the lab with radioactivity? test the niobium sample to see whether it now contains other elements.test the niobium sample for the presence of niobium oxide compounds.heat the niobium, and see if the level of radioactivity in the lab increases.place the niobium under pressure, and see if the level of radioactivity in the lab increases.