What is the concentration of X2 - in a 0.150 M solution of the diprotic acid H2X? For H2X, Ka1 = 4.5 * 10-6 and Ka2 = 1.2 * 10-11.
a) 9.9 * 10-8 M
b) 2.0 * 10-9 M
c) 8.2 * 10-4 M
d) 1.2 * 10-11 M