`H_2SO_4` is not used for the preparation of ` CO_2` from marble chips as the reaction is vigorrous .

Explanation

To understand why `H2SO4` (sulfuric acid) is not used for the preparation of `CO2` from marble chips (calcium carbonate), we can break down the explanation step by step:

### Step 1: Identify the Reactants
The reactants in this reaction are marble chips, which are primarily composed of calcium carbonate (`CaCO3`), and sulfuric acid (`H2SO4`).

### Step 2: Write the Reaction Equation
When calcium carbonate reacts with sulfuric acid, the chemical reaction can be represented as:
\[ \text{CaCO}_3 (s) + \text{H}_2\text{SO}_4 (aq) \rightarrow \text{CaSO}_4 (s) + \text{H}_2\text{O} (l) + \text{CO}_2 (g) \]

### Step 3: Analyze the Products
From the reaction, we can see that the products formed are:
- Calcium sulfate (`CaSO4`)
- Water (`H2O`)
- Carbon dioxide (`CO2`)

### Step 4: Consider the Solubility of Calcium Sulfate
Calcium sulfate is largely insoluble in water. When it forms during the reaction, it precipitates out and creates a solid layer around the remaining marble chips.

### Step 5: Understand the Implication of the Precipitate
The formation of this insoluble calcium sulfate precipitate effectively covers the marble chips. This layer prevents further contact between the unreacted marble chips and the sulfuric acid, thus inhibiting the reaction from continuing.

### Step 6: Compare with Other Acids
In contrast, if hydrochloric acid (`HCl`) were used instead of sulfuric acid, the reaction would yield calcium chloride (`CaCl2`), which is highly soluble in water. This solubility allows the acid to continue reacting with any unreacted marble chips, facilitating the production of carbon dioxide.

### Conclusion
Due to the vigorous nature of the reaction between `H2SO4` and marble chips, and the formation of an insoluble product that inhibits further reaction, sulfuric acid is not suitable for the preparation of `CO2` from marble chips.

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