Suppose 0.50 L of a HNO3 solution has a pH of 3.30. How many moles of HNO3 must have been initially dissolved in the solution?
a. 2.5x10-4 moles
b. 5.0x10-4 moles
c. 1.7x10-3 moles
d. 1.0x10-3 moles
e. 1.8x10-2 moles