In the following sets of resonance forms, label the major and minor contributors and state which structures would be of equal energy. Add any missing resonance forms.
`[CH_(3) - overset(-)overset(..)C-C -=N: hArr CH_(3) - CH = C = overset(..)N:^(-)]`

Answer

To solve the problem, we need to analyze the given resonance structures and determine which are the major and minor contributors based on their stability. We will also check for any missing resonance forms.

### Step-by-Step Solution:

1. **Identify the Given Resonance Structures:**
The two resonance forms provided are:
- Structure 1: CH₃ - C⁻ - C ≡ N
- Structure 2: CH₃ - C = C = N⁻

2. **Analyze Stability of Each Structure:**
- **Structure 1 (CH₃ - C⁻ - C ≡ N):**
- Here, the negative charge is on the carbon atom, which is less electronegative than nitrogen. This creates charge separation, which can decrease stability.
- **Structure 2 (CH₃ - C = C = N⁻):**
- In this structure, the negative charge is on the nitrogen atom, which is more electronegative. This makes the structure more stable because the negative charge is on a more electronegative atom.

3. **Determine Major and Minor Contributors:**
- Based on the analysis, **Structure 2** (CH₃ - C = C = N⁻) is the **major contributor** because it has the negative charge on the more electronegative nitrogen atom, making it more stable.
- **Structure 1** (CH₃ - C⁻ - C ≡ N) is the **minor contributor** due to the negative charge being on a less electronegative carbon atom.

4. **Check for Missing Resonance Forms:**
- Upon analyzing the structures, it appears that there are no missing resonance forms. The two structures provided encompass the significant resonance contributors for this molecule.

5. **Equal Energy Structures:**
- Since we have identified two structures, and one is a major contributor while the other is a minor contributor, they are not of equal energy. The major contributor (Structure 2) is lower in energy (more stable) than the minor contributor (Structure 1).

### Summary of Findings:
- **Major Contributor:** CH₃ - C = C = N⁻ (Structure 2)
- **Minor Contributor:** CH₃ - C⁻ - C ≡ N (Structure 1)
- **Missing Resonance Forms:** None
- **Equal Energy Structures:** No, they are not of equal energy.