Question

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

Explanation:

• Option A: Testing for other elements doesn't relate to radioactivity source (niobium's radioactivity, not impurity - related radioactivity here).
• Option B: Testing for niobium oxide compounds doesn't confirm if the pure Nb sample is the radioactivity source.
• Option C: If heating the niobium (the suspected source) increases lab radioactivity, it suggests the Nb sample is responsible (as a radioactive source would emit more when stimulated, e.g., thermal excitation affecting decay or emission).
• Option D: Pressure on niobium isn't a typical trigger for radioactivity emission related to identifying it as a source.

Answer:

C. Heat the niobium, and see if the level of radioactivity in the lab increases.