You want to determine the protein concentration of a sample using the Biuret assay. The first step is to generate a protein standard curve using BSA. You prepare 6 tubes. Tube 1 should contain 0.2 ml phosphate buffer (this will be your blank), and tubes 2-6 should contain 0.2 ml of the standard solutions (see chart below). From starting solutions containing PBS and 20.0 mg/ml BSA, you will need to calculate the volumes needed to produce standards containing 1 mg/ml, 2 mg/ml, 5 mg/ml, 10 mg/ml, and 20 mg/ml protein. Complete the chart below.