A colloidal solution of gold nanoparticles is prepared by reduction of $HAuCl_4$. Which of the following methods is MOST EFFECTIVE for purifying this solution from excess reactants and small ionic byproducts?

What weight of ${\rm{HN}}{{\rm{O}}_3}$ is needed to convert 5 g of iodine into iodic acid according to the reaction, ${{\rm{I}}_2} + {\rm{HN}}{{\rm{O}}_3} o {\rm{HI}}{{\rm{O}}_3} + {\rm{N}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}}?$ ?

What weight of ${\rm{HN}}{{\rm{O}}_3}$ is needed to convert 5 g of iodine into iodic acid according to the reaction, ${{\rm{I}}_2} + {\rm{HN}}{{\rm{O}}_3} o {\rm{HI}}{{\rm{O}}_3} + {\rm{N}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}}?$ ?

The number of moles of $KMn{O_4}$ that will be needed to react completely with one mole of oxalate ion in acidic solution is