Question- Part A: What is the pH of a buffer prepared by adding 0.708 mol of the weak acid HA to 0.507 mol of NaA in 2.00L of solution?

Part B: What is the pH after 0.150 mol of HCl is added to the buffer from Part A? Assume no volume change on the addition of the acid.

Part C: What is the pH after 0.195 mol of NaOH is added to the buffer from Part A? Assume no volume change on the addition of the base.

I need proficient help in the above problems.