Since, Fe(OH)3 is positively charged sol, hence, anionic charge will flocculate As per Hardy Schulze rules coagulation power of anion follows the order : Fe(CN)63−>CrO42−>Cl−=Br−=NO3− Higher the coagulation power lower will be its flocculation value therefore order will be : Fe(CN)63−<CrO42−<Cl−=Br−=NO3−