An original solution of an inorganic salt in dilute `HCl` gives a brown colouration with potassium hexacyanidoferrate `(III)` and reddish brown colouration with sodium acetate solution. The cation of the
salt is `:`

Options

A. `Ni^(2+)`
B. `Fe^(3+)`
C. `Cu^(2+)`
D. none

Explanation

To determine the cation of the inorganic salt based on the given reactions, we will analyze the information step by step.

### Step 1: Analyze the Reaction with Potassium Hexacyanidoferrate (III)
- The original solution of the inorganic salt in dilute HCl gives a brown coloration when mixed with potassium hexacyanidoferrate (III).
- The brown coloration indicates the presence of Fe³⁺ ions. The reaction can be represented as:

\[ \text{Fe}^{3+} + \text{[Fe(CN)₆]}^{3-} \rightarrow \text{Fe}_3[\text{Fe(CN)}_6] \text{ (brown complex)} \]

### Step 2: Analyze the Reaction with Sodium Acetate
- The solution also gives a reddish-brown coloration with sodium acetate.
- The reaction can be represented as follows:

\[ \text{Fe}^{3+} + \text{CH}_3\text{COO}^- \rightarrow \text{Fe(CH}_3\text{COO)}_3 + \text{H}^+ \]

- The reddish-brown coloration indicates the formation of a complex with acetate ions, which is consistent with the presence of Fe³⁺ ions.

### Step 3: Conclusion
- Based on the reactions observed, the cation of the inorganic salt is confirmed to be **Fe³⁺**.

### Final Answer
The cation of the salt is **Fe³⁺**.

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