Round your answers to two or three significant figures, as appropriate. 1. a. What is the concentration of HCl with a pH of 3.7? b. What is the pH of a mixture of equal volumes of 0.50 mM HCl and 0.80 mM KOH? c. What is the pH of a 12 mM nitrous acid, HNO2 (pKa 3.23).? Since nitrous acid is a weak, partially dissociated acid, use its Ka equation to determine [H+], then convert to pH. d. What is the pH of a mixture of equal volumes of 0.90 mM nitrous acid and 0.40 mM KOH? e. What concentration of formic acid will have a pH of 5.50? (pKa of formic acid = 3.75)