Most contributing structure in introethene is :

Options

A.
B.
C.
D.

Explanation

To determine the most contributing structure of nitroethane, we need to analyze the resonance structures of the molecule. Nitroethane has the formula C2H5NO2, and we can draw several resonance structures to evaluate their stability.

### Step-by-Step Solution:

1. **Draw the Lewis Structure of Nitroethane**:
- Start by drawing the basic structure of nitroethane. Nitroethane consists of an ethyl group (C2H5) attached to a nitro group (NO2).
- The nitro group has a nitrogen atom bonded to two oxygen atoms, with one of the oxygen atoms typically having a negative charge and the nitrogen having a positive charge.

2. **Identify Possible Resonance Structures**:
- Draw the resonance structures by moving the electrons around. For nitroethane, you can have several resonance forms:
- One structure with a double bond between nitrogen and one oxygen, and a single bond with the other oxygen carrying a negative charge.
- Another structure where the double bond is between nitrogen and the other oxygen, with the first oxygen carrying a negative charge.

3. **Evaluate the Charge Distribution**:
- In each resonance structure, evaluate the formal charges on each atom. The most stable structure will have the least amount of charge separation.
- Generally, structures where negative charges are on more electronegative atoms (like oxygen) and positive charges on less electronegative atoms (like carbon) are more stable.

4. **Assess the Stability of Each Structure**:
- Compare the resonance structures based on the charge distribution. The structure with the least formal charge and with charges on the most electronegative atoms will be the most stable.
- The structure with the lowest charge separation and the most neutral character will be the most contributing structure.

5. **Conclusion**:
- After evaluating the resonance structures, the most contributing structure of nitroethane is the one where the negative charge is on the oxygen atom, and the positive charge is minimized, leading to a more neutral overall charge distribution.