Ha is a weak acid its ionization constant ka is 53 x 10-13

Question

Question 1: HA is a weak acid. Its ionization constant, K_a, is 5.3 x 10^-13. Calculate the pH of an aqueous solution with an initial NaA concentration of 0.079 M. 

Question 2: We place 0.148 mol of a weak acid, HA, in enough water to produce 1.00 L of solution. The final pH of the solution is 1.27 . Calculate the ionization contant, K_a, of HA.

Question 3: We place 0.694 mol of a weak acid, HA, and 11.9 g of NaOH in enough water to produce 1.00 L of solution. The final pH of this solution is 4.74. Calculate the ionization constant, K_a, of HA.