MHTCET 18 Apr 2026 Shift 1 Paper

Concept:For a positive sol, coagulation is brought about by anions, and their coagulating power increases with the valency of the anion.Explanation:According to the Hardy-Schulze rule, higher the charge on the coagulating ion, greater is its coagulating power.Since the sol is positive, the anions are the effective coagulating ions.Now compare the charges on the given anions:$\mathrm{Cl}^{-}$ carries a charge of $-1$.$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$ carries a charge of $-4$.$\mathrm{PO}_{4}^{2-}$ carries a charge of $-2$.$\mathrm{SO}_{4}^{2-}$ carries a charge of $-2$.Clearly, $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$ has the highest negative charge.Therefore, it possesses the greatest power of coagulation for the positive sol.Note: Even if the phosphate ion is corrected to $\mathrm{PO}_{4}^{3-}$, its coagulating power remains less than that of $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$.Answer:Option B: $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$