Which one of the following statement is not correct

Options

A. Zinc dissolves in sodium hydroxide solution
B. Carbon monoxide reduces iron (III) oxides to iron
C. Mercury (II) iodine dissolves in excess of potassium iodine solution
D. Tin (IV) chloride is made by dissolving tin solution in concentrated hydrochloric acid

Answer

To determine which statement is not correct, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** Zinc dissolves in sodium hydroxide solution.

- **Explanation:** Zinc (Zn) reacts with sodium hydroxide (NaOH) to form sodium zincate (Na2ZnO2) and hydrogen gas. This reaction confirms that zinc does dissolve in sodium hydroxide.
- **Conclusion:** This statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement:** Carbon monoxide reduces iron.

- **Explanation:** Carbon monoxide (CO) can reduce iron oxides (like Fe2O3) to iron (Fe). The reaction can be represented as:
\[ \text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2 \]
- **Conclusion:** This statement is **correct**.

### Step 3: Analyze the Third Statement
**Statement:** Mercury(II) iodide dissolves in excess potassium iodide solution.

- **Explanation:** Mercury(II) iodide (HgI2) reacts with potassium iodide (KI) to form a complex ion, tetaiodomercurate(II) ion (K2HgI4). The reaction is:
\[ \text{HgI}_2 + 2\text{KI} \rightarrow \text{K}_2\text{HgI}_4 \]
- **Conclusion:** This statement is **correct**.

### Step 4: Analyze the Fourth Statement
**Statement:** Tin(IV) chloride is made by dissolving tin in concentrated hydrochloric acid.

- **Explanation:** Tin(IV) chloride (SnCl4) is not produced by simply dissolving tin in hydrochloric acid (HCl). Instead, it is formed by the reaction of tin with chlorine gas (Cl2):
\[ \text{Sn} + 2\text{Cl}_2 \rightarrow \text{SnCl}_4 \]
- **Conclusion:** This statement is **not correct**.

### Final Conclusion
The statement that is **not correct** is the fourth statement: "Tin(IV) chloride is made by dissolving tin in concentrated hydrochloric acid."

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