When the concentration of A in the reaction A B was changed from 1.20 M to 0.60 M, the half-life increased from 2.0 min to 4.0 min at 25°C. Calculate the order of the reaction and the rate constant.

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.