But-1-yne and But-2-yne can be distinguished by :

Options

A. (a)`Br_(2)//C Cl_(4)`
B. (b)`KMnO_(4)//overset(Theta)(O)H aq.("cold")`
C. (c)`(AgNO_(3)+NH_(4)OH)`
D. (d)All

Answer

To distinguish between But-1-yne and But-2-yne, we can follow these steps:

### Step 1: Understand the Structures
- **But-1-yne (1-butyne)** has the structure:
\[ CH_3-CH_2-C \equiv CH \]
- **But-2-yne (2-butyne)** has the structure:
\[ CH_3-C \equiv C-CH_3 \]

### Step 2: Identify the Reagents
We will use three different reagents to test the two compounds:
1. Bromine in CCl4
2. Potassium permanganate (KMnO4)
3. Silver nitrate (AgNO3) in the presence of ammonium hydroxide (NH4OH)

### Step 3: Test with Bromine in CCl4
- When both But-1-yne and But-2-yne are treated with Br2 in CCl4, they will undergo addition reactions.
- The reddish-brown color of bromine will disappear, indicating the addition of bromine to both compounds.
- **Conclusion**: This reagent does not distinguish between the two compounds.

### Step 4: Test with KMnO4
- When both compounds are treated with KMnO4 in a basic medium, they will be oxidized to carboxylic acids.
- Both But-1-yne and But-2-yne will yield similar products (carboxylic acids).
- **Conclusion**: This reagent also does not distinguish between the two compounds.

### Step 5: Test with AgNO3 and NH4OH
- When But-1-yne is treated with AgNO3 in the presence of NH4OH, it reacts to form a white precipitate of silver acetylide:
\[ CH_3-CH_2-C \equiv CAg \quad (\text{white precipitate}) \]
- However, But-2-yne does not have an alpha hydrogen available for this reaction, so no precipitate will form.
- **Conclusion**: This reagent successfully distinguishes between But-1-yne (which gives a white precipitate) and But-2-yne (which does not react).

### Final Conclusion
But-1-yne and But-2-yne can be distinguished using AgNO3 in the presence of NH4OH, as But-1-yne will produce a white precipitate while But-2-yne will not.

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