Which of the following ions will have minimum coagulating value for the sol obtained by adding `FeC_3` solution to slight excess of NaOH?

Options

A. `SO_4^(2-)`
B. `[Fe_6^(3) `
C. `Ba^(+)`
D. `AI^(3+)`

Explanation

To solve the problem of determining which ion has the minimum coagulating value for the sol obtained by adding FeCl3 solution to a slight excess of NaOH, we can follow these steps:

### Step 1: Understand the Reaction
When FeCl3 is added to a slight excess of NaOH, a precipitate of iron(III) hydroxide, Fe(OH)3, is formed. The reaction can be represented as:
\[ \text{FeCl}_3 + 3 \text{NaOH} \rightarrow \text{Fe(OH)}_3 \downarrow + 3 \text{NaCl} \]

### Step 2: Identify the Nature of the Precipitate
Fe(OH)3 is a colloidal precipitate that can exist in a sol state. The particles of Fe(OH)3 are larger than 1000 nm initially, but upon peptization (breaking down into smaller particles), they become smaller than 1000 nm and acquire a negative charge due to the preferential adsorption of OH- ions.
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