In one step, ethyne can be obtained from ______

Options

A. ethanol
B. ethanal
C. chloroform
D. ethyl bromide

Answer

To solve the question of how ethyne can be obtained in one step, we will analyze the options provided and identify the correct one.

### Step-by-Step Solution:

1. **Understanding Ethyne**: Ethyne, also known as acetylene, is a hydrocarbon with the formula C₂H₂, which can be represented as H-C≡C-H. It has a triple bond between the two carbon atoms.

2. **Analyzing the Options**:
- **Option 1: Ethanol (C₂H₅OH)**: Ethanol can be dehydrated to form ethylene, but it does not directly yield ethyne in one step.
- **Option 2: Ethanol (C₂H₅OH)**: This is the same as option 1 and has the same reasoning.
- **Option 3: Chloroform (CHCl₃)**: Chloroform can react with silver to produce ethyne.
- **Option 4: Ethyl bromide (C₂H₅Br)**: Ethyl bromide can undergo elimination reactions but does not directly yield ethyne in one step.

3. **Chemical Reaction for Chloroform**:
- Chloroform (CHCl₃) can be treated with silver (Ag) to remove chlorine atoms. The reaction can be represented as:
\[ 6 \text{CHCl}_3 + 6 \text{Ag} \rightarrow \text{C}_2\text{H}_2 + 6 \text{AgCl} \]
- This reaction shows that chloroform can be converted to ethyne in a single step by using silver.

4. **Conclusion**: The only option that allows the formation of ethyne in one step is chloroform.

### Final Answer:
Ethyne can be obtained from **chloroform**.

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