The arsenic in a 1.22-g sample of a pesticide was converted to AsO43- by suitable chemical treatment.

Question:

The arsenic in a 1.22-g sample of a pesticide was converted to AsO43- by suitable chemical treatment. It was then titrated using Ag+ to form Ag3AsO4 as a precipitate.
(a) What is the oxidation state of As in AsO43-?
(b) Name Ag3AsO4 by analogy to the corresponding compound containing phosphorus in place of arsenic.
(c) If it took 25.0 mL of 0.102 M Ag+ to reach the equivalence point in this titration, what is the mass percentage of arsenic in the pesticide?