Question

Which from following anions has maximum coagulating power for precipitation of positive sol?

• A. $[Fe(CN)_6]^{4-}$
• B. $Cl^-$
• C. $SO_4^{--}$
• D. $PO_4^{--}$

Answer 1

Answer: (A)

$[Fe(CN)_6]^{4-}$

Answer 2

According to the Schulze-Hardy rule, the coagulating (precipitating) power of an ion increases dramatically with its charge. Among the given anions, $[Fe(CN)_6]^{4-}$ has the highest negative charge. Therefore, it will have the maximum coagulating power for a positive sol.