Please answer parts A-C for full upvote. Thank you in advance.

The amino acid glycine is often used as the main ingredient of a buffer in biochemical experiments. The amino group of glycine, which has a pKa of 9.6, can exist either in the protonated form (NH3+ or as the free base (NH2), because of the reversible equilibrium RNH3+RNH2 (a) In what pH range can glycine be used as an effective buffer due to its amino group? (b) In a 0.1M solution of glycine at pH7.0, what is the ratio of acid/base in this equilibrium in the NH3+form? (c) what is the ratio at pH of 12