Base strength of
`(1) H_(3)Coverset(Theta)(C)H_(2), (2) H_(2)C=overset(Theta)(C)H` and (3) `H-C-=overset(Theta)(C)` is in the order of

Options

A. (a) (i) `gt` (iii) `gt` (ii)
B. (b) (i) `gt` (ii) `gt`(iii)
C. (c) (ii) `gt` (i) `gt` (iii)
D. (d) (iii) `gt` (ii) `gt` (i)

Explanation

To determine the base strength of the given species:
1. \( \text{H}_3\text{C}-\overset{\Theta}{\text{C}}-\text{H}_2 \) (which is \( \text{CH}_3\text{CH}_2^- \))
2. \( \text{H}_2\text{C}=\overset{\Theta}{\text{C}}-\text{H} \) (which is \( \text{CH}_2=\overset{\Theta}{\text{C}}^- \))
3. \( \text{H}-\overset{\Theta}{\text{C}} \) (which is \( \text{HC} \equiv \overset{\Theta}{\text{C}}^- \))

We will analyze the basic strength based on the acidity of their corresponding conjugate acids.

### Step 1: Identify the conjugate acids
- For \( \text{CH}_3\text{CH}_2^- \), the conjugate acid is \( \text{CH}_3\text{CH}_3 \).
- For \( \text{CH}_2=\overset{\Theta}{\text{C}}^- \), the conjugate acid is \( \text{CH}_2=\overset{\Theta}{\text{C}} \) (which is \( \text{C}_2\text{H}_4 \)).
- For \( \text{HC} \equiv \overset{\Theta}{\text{C}}^- \), the conjugate acid is \( \text{HC} \equiv \overset{\Theta}{\text{C}} \) (which is \( \text{C}_2\text{H}_2 \)).

### Step 2: Determine the acidity of the conjugate acids
- The acidity of the conjugate acids can be compared based on the hybridization of the carbon atoms:
- \( \text{CH}_3\text{CH}_3 \) (sp³ hybridized) has 25% s-character.
- \( \text{C}_2\text{H}_4 \) (sp² hybridized) has 33% s-character.
- \( \text{C}_2\text{H}_2 \) (sp hybridized) has 50% s-character.

### Step 3: Order the acidity based on s-character
- The order of acidity based on s-character is:
- \( \text{C}_2\text{H}_2 \) (most acidic, sp hybridized)
- \( \text{C}_2\text{H}_4 \) (moderately acidic, sp² hybridized)
- \( \text{CH}_3\text{CH}_3 \) (least acidic, sp³ hybridized)

### Step 4: Determine the order of basic strength
- Since stronger acids have weaker conjugate bases, the order of basic strength will be the opposite of the order of acidity:
- \( \text{CH}_3\text{CH}_2^- \) (strongest base)
- \( \text{CH}_2=\overset{\Theta}{\text{C}}^- \) (moderate base)
- \( \text{HC} \equiv \overset{\Theta}{\text{C}}^- \) (weakest base)

### Conclusion
Thus, the order of base strength is:
\[ \text{CH}_3\text{CH}_2^- > \text{CH}_2=\overset{\Theta}{\text{C}}^- > \text{HC} \equiv \overset{\Theta}{\text{C}}^- \]

### Final Answer
The correct order is \( 1 > 2 > 3 \), which corresponds to option B.

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