Which one of the following statement is/are correct?

Options

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

Answer

To determine which of the statements provided are correct, we will analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** Zinc dissolved in Sodium Hydroxide solution.

- **Reaction:** When zinc (Zn) reacts with sodium hydroxide (NaOH), it forms sodium zincate (Na2ZnO2) and hydrogen gas (H2).

\[ \text{Zn} + 2 \text{NaOH} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2 \]

- **Conclusion:** This statement is correct because zinc does indeed dissolve in sodium hydroxide to form a soluble salt and hydrogen gas.

### Step 2: Analyze Statement B
**Statement B:** Carbon monoxide reduces iron oxide to iron.

- **Reaction:** Carbon monoxide (CO) can reduce iron(III) oxide (Fe2O3) to iron (Fe) while itself being oxidized to carbon dioxide (CO2).

\[ \text{Fe}_2\text{O}_3 + 3 \text{CO} \rightarrow 2 \text{Fe} + 3 \text{CO}_2 \]

- **Conclusion:** This statement is also correct as carbon monoxide is a good reducing agent.

### Step 3: Analyze Statement C
**Statement C:** Mercury(II) iodide dissolved in excess of potassium iodide solution.

- **Reaction:** Mercury(II) iodide (HgI2) reacts with potassium iodide (KI) to form a soluble complex, potassium tetraiodomercurate(II) (K2HgI4).

\[ \text{HgI}_2 + 4 \text{KI} \rightarrow \text{K}_2\text{HgI}_4 + 2 \text{I}_2 \]

- **Conclusion:** This statement is correct because HgI2 does dissolve in excess KI to form a soluble compound.

### Step 4: Analyze Statement D
**Statement D:** Tin fluoride is made by dissolving tin in concentrated HCl.

- **Reaction:** Tin (Sn) does not react with concentrated HCl to form tin fluoride (SnF4). Instead, tin reacts with chlorine gas (Cl2) to form tin(IV) chloride (SnCl4).

\[ \text{Sn} + 2 \text{Cl}_2 \rightarrow \text{SnCl}_4 \]

- **Conclusion:** This statement is incorrect as tin fluoride is not produced by this method.

### Final Conclusion
- **Correct Statements:** A, B, and C are correct.
- **Incorrect Statement:** D is incorrect.

### Summary of Correct Statements:
1. **Statement A:** Correct
2. **Statement B:** Correct
3. **Statement C:** Correct
4. **Statement D:** Incorrect