A student dissolves 0.200 mol of hypochlorous acid, HOCl (Ka=3.5×10−8), and 0.100 mol of pyridine, C5H5N (Kb=1.7×10−9), in water to prepare 1.00 L of solution at 25 °C. After the acid–base reaction reaches equilibrium, what is the pH of the solution?
a) 7.5
b) 6.3
c) 5.8
d) 8.4