Inductive effect is a polarisation of a

Options

A. sigma bond
B. `pi`-bond
C. co-ordinate bond
D. conjugated system.

Answer

### Step-by-Step Solution:

1. **Understanding Inductive Effect**:
- The inductive effect refers to the polarization of a bond due to the electronegativity differences between atoms. It is primarily observed in sigma (σ) bonds.

2. **Definition of Inductive Effect**:
- The inductive effect can be defined as the polarization of a sigma bond caused by the electron-withdrawing or electron-donating effects of adjacent groups or atoms.

3. **Types of Inductive Effect**:
- There are two types of inductive effects:
- **Negative Inductive Effect (-I)**: Caused by electron-withdrawing groups (e.g., halogens like Cl, Br).
- **Positive Inductive Effect (+I)**: Caused by electron-donating groups (e.g., alkyl groups like CH3).

4. **Example of Inductive Effect**:
- Consider a molecule like CH3-CH2-CH2-CH2-Cl. The chlorine atom is an electron-withdrawing group. It pulls electron density away from the carbon chain, creating a partial positive charge on the adjacent carbon atoms and a partial negative charge on itself.

5. **Distance Dependence**:
- The inductive effect is distance-dependent. The effect diminishes with increasing distance from the electronegative atom or group. For example, the carbon atom directly attached to Cl will have a greater positive charge than the carbon atom two bonds away.

6. **Comparison with Other Bond Types**:
- **Pi Bonds**: Inductive effect does not occur in pi bonds because they are involved in resonance, which is a different phenomenon.
- **Coordinate Bonds**: In coordinate bonds, one atom donates both electrons to form the bond, and there is no polarization involved.
- **Conjugated Systems**: In conjugated systems, resonance occurs, which involves the delocalization of pi electrons rather than polarization of sigma bonds.

7. **Conclusion**:
- The inductive effect is specifically the polarization of a sigma bond due to the influence of adjacent electron-withdrawing or electron-donating groups.

### Final Answer:
- **Inductive effect is a polarization of a sigma bond.**