`underset((I))(CH_(3)COOH)" "underset((II))(CH_(3)COONa)" "underset((III))(CH_(3)CONH_(2))`
Among these compounds, the correct order of resonance energy is

Options

A. `I gt II gt III`
B. `III gt II gt I`
C. `II gt III gt I `
D. `II gt I gt III`

Answer

To determine the correct order of resonance energy among the compounds CH₃COOH (I), CH₃COONa (II), and CH₃CONH₂ (III), we need to analyze the resonance structures of each compound and assess their stability.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Functional Groups:**
- (I) CH₃COOH: Acetic acid, which contains a carboxylic acid functional group.
- (II) CH₃COONa: Sodium acetate, which is a salt of acetic acid.
- (III) CH₃CONH₂: Acetamide, which contains an amide functional group.

2. **Draw the Resonance Structures for Each Compound:**
- **For CH₃COOH:**
- The resonance structures involve the movement of the lone pairs on the oxygen atoms.
- One possible resonance structure shows a double bond between carbon and one oxygen, while the other oxygen carries a negative charge. However, this structure has a positive charge on the other oxygen, which is less stable due to oxygen's high electronegativity.

- **For CH₃COONa:**
- The resonance structures can show the negative charge on the oxygen being delocalized over the two oxygen atoms.
- This results in equivalent resonance structures, which are more stable because the negative charge is distributed.

- **For CH₃CONH₂:**
- The resonance structures involve the nitrogen atom. The lone pair on nitrogen can participate in resonance with the carbonyl group, leading to a structure where nitrogen carries a positive charge.
- Since nitrogen is less electronegative than oxygen, this structure is more stable compared to the resonance structures of acetic acid.

3. **Assess the Stability of the Resonance Structures:**
- **Stability Order:**
- CH₃COONa (II) has the most stable resonance structures due to equivalent resonance forms that distribute the negative charge effectively.
- CH₃CONH₂ (III) has stable resonance structures, but the positive charge on nitrogen is less destabilizing than the positive charge on oxygen in acetic acid.
- CH₃COOH (I) has the least stable resonance structures due to the presence of a positive charge on the electronegative oxygen atom.

4. **Determine the Order of Resonance Energy:**
- Based on the stability of the resonance structures, the order of resonance energy from highest to lowest is:
- CH₃COONa (II) > CH₃CONH₂ (III) > CH₃COOH (I)

### Final Answer:
The correct order of resonance energy is:
**CH₃COONa (II) > CH₃CONH₂ (III) > CH₃COOH (I)**