The correct trend of acidic nature of the following alkynes is

Options

A. `CH-=CH gt CH_(3) - C-=CH gt CH_(3) C -=C CH_(3)`
B. `CH_(3)-C -=CH gt CH -= CH gt CH_(3) C -= C CH_(3)`
C. `CH_(3)C -= C CH_(3) gt CH_(3 - C-=CH gt CH -= CH`
D. `CH-=CH gt CH_(3)C -= C CH_(3) gt CH_(3) C -=CH`

Answer

To determine the correct trend of acidic nature among the given alkynes, we need to analyze the factors that affect the acidity of alkynes. Here’s a step-by-step solution:

### Step 1: Understand the Factors Affecting Acidity
The acidity of alkynes is influenced primarily by two factors:
1. **Inductive Effect (+I effect)**: Electron-donating groups increase electron density at the carbon atom of the alkyne, which reduces the polarity of the C-H bond and consequently decreases acidity.
2. **Polarity of C-H Bond**: The more polar the C-H bond, the stronger the acid.

### Step 2: Analyze the Given Alkynes
Let’s analyze the acidic strength of the alkynes based on the presence of substituents:

- **Alkyne A (CH≡CH)**: This alkyne has no substituents. Therefore, it has the highest acidity because there are no electron-donating groups to decrease the polarity of the C-H bond.

- **Alkyne B (CH3C≡CH)**: Here, a methyl group (CH3) is attached to one of the carbons of the alkyne. The methyl group is an electron-donating group, which increases the electron density around the carbon and decreases the polarity of the C-H bond. Thus, the acidity is lower than that of alkyne A.

- **Alkyne C (CH3C≡CCH3)**: In this case, two methyl groups are attached to the alkyne. The presence of two electron-donating groups further increases the electron density and decreases the polarity of the C-H bond even more than in alkyne B. Therefore, this alkyne has the lowest acidity among the three.

### Step 3: Establish the Trend
Based on the analysis:
- Alkyne A (CH≡CH) is the most acidic.
- Alkyne B (CH3C≡CH) is less acidic than A.
- Alkyne C (CH3C≡CCH3) is the least acidic.

Thus, the correct trend of acidic nature is:
**CH≡CH > CH3C≡CH > CH3C≡CCH3**

### Conclusion
The correct order of acidity among the given alkynes is:
**Option A: CH≡CH > CH3C≡CH > CH3C≡CCH3**

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