Assertion. But 1-yne and but-2-yne can be distinguished by ammoniacal silver nitration solution
Reason. 1-Butyne forms white ppt. with ammoniacal silver nitrate but 2-butyne does not

Options

A. If both assertion and reason are true, and reason is the true explanation of the assertion.
B. If both assertion and reason are true, but reason is not the true explanation of the assertion.
C. If assertion is true, but reason is false.
D. If both assertion and reason are false

Answer

To solve the assertion-reason question regarding but-1-yne and but-2-yne, we will analyze both the assertion and the reason step by step.

### Step-by-Step Solution:

1. **Understanding the Compounds**:
- But-1-yne (C4H6) has the structure CH3-CH2-C≡C-H. It has a terminal triple bond, which means it has an acidic hydrogen atom (the hydrogen attached to the carbon with the triple bond).
- But-2-yne (C4H6) has the structure CH3-C≡C-CH3. It has an internal triple bond and does not have any acidic hydrogen atoms.

2. **Ammoniacal Silver Nitrate Test**:
- Ammoniacal silver nitrate (also known as Tollens' reagent) is used to test for terminal alkynes. The acidic hydrogen of terminal alkynes can react with the silver ion (Ag+) in the reagent.
- When but-1-yne is treated with ammoniacal silver nitrate, the acidic hydrogen reacts, leading to the formation of a white precipitate of silver acetylide (AgC≡C-R).

3. **Reaction of But-1-yne**:
- The reaction of but-1-yne with ammoniacal silver nitrate will yield a white precipitate due to the formation of silver acetylide.
- The equation can be represented as:
\[ \text{AgNO}_3 + \text{CH}_3\text{CH}_2\text{C}\equiv\text{C-H} \rightarrow \text{AgC}\equiv\text{C} + \text{other products} \]
- The formation of this white precipitate confirms the presence of a terminal alkyne.

4. **Reaction of But-2-yne**:
- In contrast, but-2-yne does not react with ammoniacal silver nitrate because it does not have an acidic hydrogen atom. Therefore, no precipitate is formed.
- The absence of a reaction can be summarized as:
\[ \text{AgNO}_3 + \text{CH}_3\text{C}\equiv\text{C}\text{CH}_3 \rightarrow \text{No reaction} \]

5. **Conclusion**:
- Since but-1-yne forms a white precipitate with ammoniacal silver nitrate while but-2-yne does not, we can conclude that the assertion is true and the reason provided is also true and correctly explains the assertion.

### Final Answer:
Both the assertion and reason are true, and the reason is a correct explanation for the assertion.

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