Acetaldehyde and Propyne can be distinguish by :
(i) Tollen's reagent " " (ii) `l_(2)//NaOH` " " (iii) Lucas reagent " " (iv) neutral `FeCl_(3)`

Options

A. (i), (ii) & (iii)
B. (ii) & (iii)
C. (i) & (ii)
D. (iii) & (iv)

Explanation

To distinguish between acetaldehyde and propyne, we can use the following tests:

1. **Tollens' Reagent Test**:
- **Explanation**: Tollens' reagent (Ag(NH3)2^+) is a test specifically for aldehydes. Acetaldehyde, being an aldehyde, will react with Tollens' reagent to form a silver mirror, while propyne, being an alkyne, will not react.
- **Conclusion**: This test can distinguish acetaldehyde from propyne.

2. **Iodine and Sodium Hydroxide (I2/NaOH) Test**:
- **Explanation**: This is known as the Iodoform test. It is positive for compounds that have the structure CH3C(=O)R, where R can be hydrogen or another carbon chain. Acetaldehyde (CH3CHO) fits this structure and will give a yellow precipitate of iodoform (CHI3) when treated with I2/NaOH. Propyne does not have this structure and will not give a positive result.
- **Conclusion**: This test can also distinguish acetaldehyde from propyne.

3. **Lucas Reagent Test**:
- **Explanation**: Lucas reagent is used to test for the presence of alcohols (1°, 2°, and 3°). Neither acetaldehyde nor propyne is an alcohol, so this test will not provide any distinguishing information between the two.
- **Conclusion**: This test is not useful for distinguishing acetaldehyde from propyne.

4. **Neutral Ferric Chloride (FeCl3) Test**:
- **Explanation**: Neutral FeCl3 is used to test for phenols, which form colored complexes with FeCl3. Since neither acetaldehyde nor propyne is a phenol, this test will not yield any results.
- **Conclusion**: This test is also not useful for distinguishing acetaldehyde from propyne.

### Final Conclusion:
The tests that can be used to distinguish acetaldehyde from propyne are:
- Tollens' reagent
- I2/NaOH (Iodoform test)

Thus, the correct answer is that acetaldehyde and propyne can be distinguished by (i) Tollens' reagent and (ii) I2/NaOH.