What is formed when oxalic acid is dehydrated by `conc. H_2 SO_4` ?

Options

A. `C + CO_2`
B. `CO`
C. `CO_2`
D. `CO + CO_2`

Answer

To determine what is formed when oxalic acid is dehydrated by concentrated sulfuric acid (H₂SO₄), we can follow these steps:

### Step 1: Understand the Structure of Oxalic Acid
Oxalic acid (C₂H₂O₄) has the following structure:
- It consists of two carboxylic acid groups (-COOH).
- The molecular formula can be represented as:
\[ HOOC-COOH \]

### Step 2: Identify the Role of Concentrated H₂SO₄
Concentrated sulfuric acid acts as a dehydrating agent. This means it can remove water (H₂O) from the reaction mixture.

### Step 3: Dehydration Reaction
When oxalic acid is treated with concentrated H₂SO₄, the following occurs:
- The -OH group from one carboxylic acid and an -H from the other carboxylic acid combine to form water (H₂O).
- This leads to the formation of an intermediate compound.

### Step 4: Formation of Products
After the removal of water, the remaining carbon atoms and oxygen atoms rearrange:
- The carbon atoms can form carbon monoxide (CO) and carbon dioxide (CO₂).
- The overall reaction can be summarized as:
\[ \text{C}_2\text{H}_2\text{O}_4 \xrightarrow{\text{conc. } H_2\text{SO}_4} \text{CO} + \text{CO}_2 + \text{H}_2\text{O} \]

### Step 5: Conclusion
Thus, when oxalic acid is dehydrated by concentrated sulfuric acid, the products formed are carbon monoxide (CO), carbon dioxide (CO₂), and water (H₂O).

### Final Answer
The products formed are:
- Carbon monoxide (CO)
- Carbon dioxide (CO₂)
- Water (H₂O)