How can a scientist assess whether a pure niobium (Nb) sample is responsible for contaminating the lab with radioactivity

Match each description to the level of organization

You are studying a protein that you call protein x. there is an aspartic acid at a key position in protein x which is important in the folding and stabilization of that protein. if this aspartic acid is changed to a different amino acid, which type of amino acid substitutions is most likely to allow the protein to fold normally?

In figure 1-2 what is the distance from point b to point c?