Which of the following statements is not true about the stability of carbanions?

Options

A. Stability of carbanions becauses with increase in s-character of orbital
B. The electron withdrawingg groups like increases the stability of carbanions.
C. Order of stability of carbanions is `3^(@) gt 2^(@) gt 1^(@)`,
D. The negatively charged carbon is `sp^(3)` hybridised and pyramidal.

Explanation

To determine which statement is not true about the stability of carbanions, we need to analyze the stability factors associated with carbanions. Here’s a step-by-step solution:

### Step 1: Understand Carbanion Stability
Carbanions are negatively charged carbon species. Their stability is influenced by several factors, including hybridization, electronegativity, and the presence of electron-donating or withdrawing groups.

**Hint:** Recall that the stability of carbanions increases with the electronegativity of the atom bearing the negative charge and the s-character of the hybrid orbital.

### Step 2: Analyze Hybridization
The stability of carbanions is affected by the hybridization of the carbon atom:
- **sp Hybridization (50% s-character)**: Most stable due to higher electronegativity.
- **sp² Hybridization (33.33% s-character)**: Less stable than sp.
- **sp³ Hybridization (25% s-character)**: Least stable.

**Hint:** Remember that greater s-character means greater stability for carbanions.

### Step 3: Consider Electron Withdrawing and Donating Groups
- **Electron-withdrawing groups (EWGs)** stabilize carbanions through their -I (inductive) effect.
- **Electron-donating groups (EDGs)** destabilize carbanions through their +I effect.

**Hint:** Identify the effect of substituents on the stability of carbanions.

### Step 4: Evaluate the Given Statements
Now, let's evaluate the statements provided in the question:

- **Option A**: Stability increases with increasing s-character.
- **Option B**: Electron-withdrawing groups stabilize carbanions.
- **Option C**: Tertiary carbanions are more stable than secondary and primary carbanions.
- **Option D**: The structure of a carbanion is pyramidal with a lone pair.

**Hint:** Compare each statement against the principles of carbanion stability discussed.

### Step 5: Identify the Incorrect Statement
From the evaluation:
- **Option A** is true.
- **Option B** is true.
- **Option C** is **not true** because tertiary carbanions are less stable than secondary and primary carbanions due to the destabilizing +I effect of alkyl groups.
- **Option D** is true.

Thus, the incorrect statement is **Option C**.

**Final Answer:** The statement that is not true about the stability of carbanions is **Option C**: Tertiary carbanions are more stable than secondary and primary carbanions.