Sodium thiosulfate (Na2S2O3) the major component in photographic fixer solution, reacts with silver bromide to dissolve it according to the following reaction:
AgBr(s) + 2 Na2S2O3(aq) → Na3Ag(S2O3)2(aq) + NaBr(aq)
b. How many mL of 0.02 M Na2S2O3 contain this number of moles?