Acetylene is obtained from `CaC_2`

Options

A. by treating it with cold water
B. heating it at ` 140^(@) C ` in the presence of `H_2SO_4`
C. by passing `H_2` over it at `1200^(@) C `
D. by passing vapours over it at `100^(@) C`

Explanation

To obtain acetylene from calcium carbide (CaC₂), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The primary reactant is calcium carbide (CaC₂), and we will be using water (H₂O) as the second reactant.

2. **Set Up the Reaction**: The reaction involves treating calcium carbide with cold water. The chemical equation for this reaction can be written as:
\[ \text{CaC}_2 + 2\text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_2 + \text{Ca(OH)}_2 \]
Here, acetylene (C₂H₂) is produced along with calcium hydroxide (Ca(OH)₂).

3. **Understand the Products**: Upon reacting with cold water, calcium carbide produces acetylene gas, which is colorless and flammable, and calcium hydroxide, which appears as a milky white precipitate.

4. **Collect the Acetylene Gas**: The acetylene gas can be collected over water or by using a gas collection setup, as it is less soluble in water compared to calcium hydroxide.

5. **Safety Considerations**: Since acetylene is highly flammable, it is important to conduct this reaction in a well-ventilated area and away from open flames.

### Final Reaction Summary:
By treating calcium carbide (CaC₂) with cold water, we successfully produce acetylene (C₂H₂) and calcium hydroxide (Ca(OH)₂).

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