Resonance is not possible in

Options

A.
B.
C.
D.

Answer

To solve the question "Resonance is not possible in", we will analyze each of the given options to determine whether resonance can occur.

### Step-by-Step Solution:

1. **Understanding Resonance**:
- Resonance involves the movement of pi electrons within a molecule. For resonance to occur, there must be:
- A lone pair of electrons on one atom.
- An adjacent atom with an empty orbital to accept those electrons.
- The atoms involved must be in the same plane.

2. **Analyzing Option 1: CH3CH(+)O(CH3)**
- In this structure, the oxygen has a lone pair of electrons and is adjacent to a carbon with a positive charge.
- The lone pair on oxygen can be donated to form a double bond with the carbon, resulting in resonance.
- **Conclusion**: Resonance is possible in this option.

3. **Analyzing Option 2: CH2=CH(+)NH3**
- Here, nitrogen has a positive charge and does not have a lone pair of electrons.
- Since nitrogen is positively charged and has only two bonds, it cannot participate in resonance because it lacks the necessary lone pair or empty orbital.
- **Conclusion**: Resonance is NOT possible in this option.

4. **Analyzing Option 3: CH2=CH-NO2**
- In this case, the nitrogen in the nitro group (NO2) has a positive charge, and the oxygen atoms have lone pairs.
- The resonance can occur as the lone pairs on the oxygen can interact with the nitrogen, allowing for electron movement and resonance structures to form.
- **Conclusion**: Resonance is possible in this option.

5. **Analyzing Option 4: CH2=CH-BH2**
- Boron (B) has an empty p-orbital and can accept electrons. The carbon-carbon double bond can interact with boron.
- The resonance can occur as the electron density shifts towards boron, allowing for resonance structures.
- **Conclusion**: Resonance is possible in this option.

### Final Answer:
- The correct answer is **Option 2: CH2=CH(+)NH3**, as resonance is not possible in this structure.