help. I need it with a full explanation and full process calculation. I'm so confused. I tried it so much and couldn't get the right answer

2. A 0.2000 M benzoic acid solution was prepared by the CHEM 201 lab students one winter, and the CHEM 203 lab sections were asked to titrate samples of this with 0.2000 M NaOH. Assume that a 50.00 mL aliquot was taken by each group of students for the titration analysis. a. Calculate the K value for the reaction between benzoic acid and NaOH. b. Calculate the pH when(0.00) 10.00, 25.00. 40.00, 50.00, and 75.00 of NaOH are added. c. Determine the Kin value of an indicator suitable to mark the equivalence point in this titration. 3, a. Sodium fluoride, NaF, is found in a variety of toothpastes. Calculate the pH of a 0.14 M NaF solution. b. Calculate the pH of a 0.22 M HF solution. c. Determine the pH of a mixture that is formed by adding 60.0 mL of 0.14 M NaF to 40.0 mL of 0.22 M HF (assume the volumes are additive), using (i) an equilibrium approach, and (ii) the Henderson-Hasselbalch equation. Left: K.A. Hasselbalch Right: L.J. Henderson d. Describe the change in pH (increase/decreaseo change) Image courtesy of to the solution given in (c) when each of the following is added: Wikicommons. (i) NaF (ii) HF (iii) HCI (iv) NaOH