Pick out the incorrect statement about CO .

Options

A. In laboratory it is prepared by dehydrating HCOOH with conc. `H_2SO_4`
B. CO is neutral oxide and acts as a fuel
C. It reduces aqueous solution of `PdCl_2` to metallic Pd
D. Co forms complex with haemoglobin and this complex is less stable than oxyhaemoglobin

Answer

To solve the question "Pick out the incorrect statement about CO (carbon monoxide)," we will analyze each of the provided statements step by step.

### Step 1: Analyze Option 1
**Statement:** In the laboratory, it is prepared by dehydrating formic acid with concentrated H2SO4.

**Analysis:**
- The reaction of formic acid (HCOOH) with concentrated sulfuric acid (H2SO4) indeed leads to the formation of carbon monoxide (CO) and water (H2O) through dehydration.
- This reaction is valid as concentrated sulfuric acid is a strong dehydrating agent.

**Conclusion:** This statement is correct.

### Step 2: Analyze Option 2
**Statement:** Carbon monoxide is a neutral oxide and acts as a fuel.

**Analysis:**
- Carbon monoxide (CO) is classified as a neutral oxide because it does not exhibit acidic or basic properties.
- Additionally, CO is indeed flammable and can act as a fuel in various chemical reactions.

**Conclusion:** This statement is also correct.

### Step 3: Analyze Option 3
**Statement:** It reduces aqueous solution of palladium chloride to metallic palladium.

**Analysis:**
- Carbon monoxide can reduce palladium chloride (PdCl2) to metallic palladium (Pd).
- The reaction can be represented as:
\[ \text{PdCl}_2 + \text{CO} + \text{H}_2\text{O} \rightarrow \text{Pd} + \text{CO}_2 + \text{HCl} \]
- This confirms that CO can indeed reduce palladium chloride.

**Conclusion:** This statement is correct.

### Step 4: Analyze Option 4
**Statement:** Carbon monoxide forms a complex with hemoglobin, and this complex is less stable than oxyhemoglobin.

**Analysis:**
- Carbon monoxide binds to hemoglobin to form carboxyhemoglobin (COHb), which is a stable complex.
- In fact, the bond between carbon monoxide and hemoglobin is significantly stronger than that of oxygen and hemoglobin (oxyhemoglobin).
- Therefore, the statement that the complex is less stable than oxyhemoglobin is incorrect.

**Conclusion:** This statement is incorrect.

### Final Answer
The incorrect statement about carbon monoxide (CO) is **Option 4**: "Carbon monoxide forms a complex with hemoglobin, and this complex is less stable than oxyhemoglobin."

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