Q1) The second protonation state for phosphoric acid (H 2 PO 4 -) has a pKa of 6.82. What is the pH where approximately 10% of the acid is in the

Q1) The second protonation state for phosphoric acid (H2PO4 -) has a pKa of 6.82. What is the pH where approximately 10% of the acid is in the protonated (H2PO4 -) form?

Q2) H2CO3 is a diprotic acid. The pKa for H2CO3 is 6.35 and the pKa for HCO3- = 10.33. At pH = 7.2, what is the approximate relative quantities of H2CO3, HCO3-, and CO32-?

Please provide explanations and step by step ( I have the answer key, just need to understand how to work the problem) 

I'll rate best answer! Thanks