Which one of the following property is not correct for ozone?

Options

A. It oxidises lead sulphide
B. It oxidises potassium iodide
C. It oxidises mercury
D. It cannot act as bleaching agent in dry state.

Explanation

To determine which property of ozone is not correct, we will analyze each of the given properties one by one.

### Step 1: Identify the properties of ozone
We know that ozone (O₃) is a gas and has several chemical properties. We will evaluate each property mentioned in the question.

### Step 2: Evaluate the first property
**Property 1:** Ozone oxidizes lead sulfide (PbS).

- **Reaction:** When lead sulfide reacts with ozone, it gets oxidized to lead sulfate (PbSO₄), and oxygen gas (O₂) is released.
- **Balanced Equation:** 4 PbS + 4 O₃ → 4 PbSO₄ + 4 O₂.
- **Conclusion:** This property is true. Ozone does oxidize lead sulfide.

### Step 3: Evaluate the second property
**Property 2:** Ozone oxidizes potassium iodide (KI).

- **Reaction:** When potassium iodide is treated with ozone in the presence of water, it forms potassium hydroxide (KOH), iodine (I₂), and oxygen gas (O₂).
- **Balanced Equation:** 2 KI + O₃ + H₂O → 2 KOH + I₂ + O₂.
- **Conclusion:** This property is also true. Ozone oxidizes potassium iodide.

### Step 4: Evaluate the third property
**Property 3:** Ozone oxidizes mercury (Hg).

- **Reaction:** When mercury reacts with ozone, it forms mercurous oxide (Hg₂O) and oxygen gas (O₂).
- **Balanced Equation:** 2 Hg + O₃ → Hg₂O + O₂.
- **Conclusion:** This property is true as well. Ozone oxidizes mercury.

### Step 5: Evaluate the fourth property
**Property 4:** Ozone cannot act as a bleaching agent in dry state.

- **Explanation:** A bleaching agent removes stains from fabrics through oxidation or reduction. Ozone decomposes to produce nascent oxygen (a single oxygen atom), which is responsible for its bleaching action.
- **Conclusion:** Ozone can act as a bleaching agent even in dry conditions because nascent oxygen is generated. Therefore, this statement is false.

### Final Answer
The property that is not correct for ozone is: **Ozone cannot act as a bleaching agent in dry state.**

### Summary of the Answer:
- The correct answer is **Property 4**: "Ozone cannot act as a bleaching agent in dry state."