The boiling point of elements in group 17 on the period table A- varies in a manner unrelated to changes in atomic number
B- increases as the atomic number increases
C- decreases as the atomic number increases
D- increases as the atomic number decreases

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.