A 100 mL solution of 0.1M glycine at ph 1.72 was titrated with 2 M NaOH solution. The ph was monitored and the results were plotted as shown in the graph above. The key points in their titration are designed I to V. For each of the statements, identify the appropriate key point in the titration.

a.) and are the best ph regions for buffering power.
b.) The ph is equal to the pKa of the amino group.
c.) The average net charge of glycine is zero.
d.) The predominant species is +H3N-CH2-COOH
e.) Glycine is present predominantly as a 50:50 mixture of +H3N-CH2-COOH and +H3N-CH2-COO-.