Answer:
The weakest conjugate base is C9H7O4⁻ which is the conjugate base of Aspirin.
Explanation:
The higher the Ka, the stronger the acid thus the weaker its conjugate base.
Ka of the acid are provided:
CH3COOH = 1.80*10-5
HC9H7O4 = 3.00*10-4
C6H5COOH = 6.30*10-5
From the Ka above, HC9H7O4 have the highest therefore its conjugate acid is the weakest.
When it donates the proton, it becomes the conjugate base.
HC9H7O4 + H2O ⇄ C9H7O4⁻ + H3O⁺
