What is the ph at the first equivalence point- what is the

Question

Consider the titration curve :-

1. What is the pH at the first equivalence point?
a. 0
b. 2
c. 4
d. 6
e. 8

2. What is the ratio of conjugate base to acid at pH = 5?
a. 1 to 10
b. 2 to 10
c. 10 to 1
d. 10 to 2
e. 1 to 1

3. What is the mole fraction of conjugate Base at pH 3?
a. 0.09
b. 0.91
c. 1.10
d. 101
e. 0.5

4. If this were the titration curve for Histidine, at what pH would the amino acid be ~ neutral?
a. 2
b. 4
c. 6
d. 8
e. 10

5. If there was 100 mL of acid at the beginning of the titration, what was the concentration of acid?
a. 0.01 M
b. 0.05 M
c. 0.10 M
d. 0.15 M
e. 0.20 M

6. At what pH would this acid be the worst buffer?
a. 1
b. 2
c. 3
d. 4
e. 5

7.What is the relevant conjugate acid and conjugate base pair at pH 3?  Assume the acid is H₃A.

a. HA^2-, A^3-

b. H₂A^-, HA^2-

c. H₃A, H₂A^-

d. H₂A^-, H₃A

e. None of the above.