Which of the following pairs of Lewis structure represent resonance contributor to the species?

Options

A. `underset(and)(H-underset(H)underset(|)(C )=overset(ddot)(N)-N " " H-overset(ddot)(C )=underset(H)underset(|)overset(+)(N)-H)`
B. `underset(and)(H-underset(H)underset(|)(C )=overset(ddot)(N)-H " " H-underset(H)underset(|)overset(+)(C )-underset(ddot)overset(-)(N)-H)`
C. `underset(and)(H-underset(H)underset(|)overset(H)overset(|)(C )=overset( :O: )overset(||)(C )-H " "H-overset(H)overset(|)(C )=overset( :O:-H )overset(|)(C )-H`
D. `underset(and)(H_3C-CH_2-underset(ddot)overset(ddot)(O)-H " "H_3C-underset(ddot)overset(ddot)(O)CH_3`

Answer

To determine which pairs of Lewis structures represent resonance contributors to a species, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand Resonance**:
- Resonance structures are different ways of drawing the same molecule that only differ in the arrangement of electrons, not in the arrangement of atoms.
- The key point is that no atoms move; only the electrons (typically pi electrons or lone pairs) are delocalized.

2. **Analyze Each Option**:
- We will evaluate each pair of Lewis structures provided in the options to see if they can be considered resonance contributors.

3. **Option A**:
- Structures: HCH double bond NN and HC double bond NHH.
- Analysis: The number of atoms differs between the two structures (one has two nitrogens, the other has one nitrogen and a hydrogen). Therefore, these cannot be resonance structures.

4. **Option B**:
- Structures: A structure with a nitrogen atom bonded to carbon and a lone pair on nitrogen, and another structure where nitrogen has a negative charge and carbon has a positive charge.
- Analysis: The electrons can be delocalized between the nitrogen and carbon. This is a valid resonance structure since the atoms remain in the same position, and only the electrons are rearranged.

5. **Option C**:
- Structures: A carbon atom forming five bonds and another structure with a lone pair on oxygen.
- Analysis: The first structure is invalid as carbon cannot form five bonds. Thus, these cannot be resonance structures.

6. **Option D**:
- Structures: CH3CH2OH and CH3OCH3.
- Analysis: The entire CH3 group is moving from one structure to another, which violates the resonance rule (no atoms can move). Therefore, these are not resonance structures.

7. **Conclusion**:
- After analyzing all options, only **Option B** contains valid resonance structures.

### Final Answer:
The correct answer is **Option B**.