Option c.is right...Bcuz lowest charge present on potassium bromide.. hence,it is least effective during flocculation

Introduction:
The flocculation of ferric hydroxide sol is the process of forming aggregates or flocs of ferric hydroxide particles in a solution. This process is induced by the addition of certain electrolytes that can neutralize the electrical charges on the ferric hydroxide particles, causing them to come together and form larger aggregates. The effectiveness of an electrolyte in causing flocculation depends on its ability to neutralize the surface charges on the particles.

Explanation:
In this question, we are asked to determine which of the given electrolytes is least effective in causing flocculation of ferric hydroxide sol. Let's analyze each option:

a) K[Fe(CN)]:
K[Fe(CN)] is potassium ferricyanide. It contains the Fe(CN) complex, which is negatively charged. When added to the ferric hydroxide sol, potassium ferricyanide can neutralize the positively charged ferric hydroxide particles, leading to flocculation. Therefore, it is an effective electrolyte for causing flocculation.

b) KCrO:
KCrO is potassium chromate. It contains the CrO4^-2 complex, which is negatively charged. Similar to potassium ferricyanide, potassium chromate can neutralize the positive charges on ferric hydroxide particles, promoting flocculation. Hence, it is an effective electrolyte for causing flocculation.

c) KBr:
KBr is potassium bromide. Unlike potassium ferricyanide and potassium chromate, potassium bromide does not contain any complex ions that can neutralize the charges on ferric hydroxide particles. It only dissociates into potassium cations (K+) and bromide anions (Br^-) in solution. These ions do not have the ability to flocculate ferric hydroxide particles. Therefore, KBr is the least effective electrolyte in causing flocculation.

d) KSO:
KSO is potassium sulfate. Similar to KBr, potassium sulfate only dissociates into potassium cations (K+) and sulfate anions (SO4^-2) in solution. These ions do not possess the ability to neutralize the charges on ferric hydroxide particles, making KSO ineffective in causing flocculation.

Conclusion:
Among the given electrolytes, KBr is the least effective in causing flocculation of ferric hydroxide sol. KBr does not contain any complex ions that can neutralize the charges on ferric hydroxide particles, unlike potassium ferricyanide and potassium chromate. KBr only dissociates into potassium cations and bromide anions, which do not have the ability to flocculate ferric hydroxide particles.