Which one of the following statements is not 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 iodide solution
D. Tin (IV) chloride is made by dissolving tin solution in concentrated hydrochloric acid

Explanation

To determine which statement is not correct, we need to analyze each of the provided statements one by one.

1. **Zinc dissolving in sodium hydroxide solution**:
- Zinc reacts with sodium hydroxide in the presence of water to form sodium zincate and hydrogen gas. This reaction is indeed correct.
- **Hint**: Remember that zinc can react with strong bases like sodium hydroxide.

2. **Carbon monoxide reduces iron(III) oxide to iron**:
- Carbon monoxide (CO) is a reducing agent and can reduce iron(III) oxide (Fe2O3) to iron (Fe). This statement is also correct.
- **Hint**: Recall the role of CO in metallurgical processes, especially in the reduction of metal oxides.

3. **Mercury(II) iodide dissolving in excess potassium iodide solution**:
- Mercury(II) iodide (HgI2) can dissolve in potassium iodide (KI) to form a complex ion, which is a correct statement.
- **Hint**: Consider the solubility of metal halides in the presence of excess halide ions.

4. **Tin(IV) chloride is made by dissolving tin in concentrated hydrochloric acid**:
- Tin(IV) chloride (SnCl4) is indeed produced when tin (Sn) reacts with concentrated hydrochloric acid (HCl). This statement is also correct.
- **Hint**: Think about the reactions of metals with acids and the oxidation states involved.

After analyzing all four statements, we find that they are all correct. However, if we were to choose one that is commonly misunderstood or misrepresented in educational contexts, it would be beneficial to clarify the nature of the reactions involved, particularly the conditions under which they occur.

In conclusion, since all statements appear to be correct, we can state that there is no incorrect statement among the options provided.

**Final Answer**: All statements are correct; there is no incorrect statement.