In a reduction-oxidation or better known as REDOX reaction, the substance that reduces the oxidation state is known as the substance that is REDUCED. It serves as the oxidizing agent. Thus, Au3+ in this number is considered as the oxidizing agent.
% error = 3.4 %
Percent error = |accepted value - experimental value|/accepted value × 100%
∴ % error = |355 mL – 343 mL|/355 mL × 100 % = |12|/355 × 100 % = 3.4 %
I think your answer is “true”, sorry if I’m wrong and hope this helps