for the next 3 questions please note that the pKa of cytosine is 4.3 20. At a pH of 7, what is the ratio of A-to HA in an aqueous solution of cytosine? A) 1:1 B)-50:1 C) -500:1 D-5000:1 E) -50000:1 21. What is the pH of a solution of cytosine, when the concentration of its acid is 100-fold higher than the concentration of base? A) 6.3 B) 4.3 C) 3.5 D) 2.3 E) 0 22. At what pH are the molar concentrations of acid and base is equal to one another? Cloud A) 6.3 B) 4.3 C) 3.5 D) 2.3 E) 0