Out of `(A)` toluene `(B)` m-dichloro benzene `(C )` o-dichloro benzene and `(D)` p-dichlorobenzene________have highest and______have lowest dipole moment.

Explanation

To determine which of the given compounds has the highest and lowest dipole moment, we will analyze the structures and the arrangement of the substituents on the benzene ring for each compound.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds to analyze:
- (A) Toluene (C7H8)
- (B) m-Dichlorobenzene (C6H4Cl2)
- (C) o-Dichlorobenzene (C6H4Cl2)
- (D) p-Dichlorobenzene (C6H4Cl2)

2. **Draw the Structures**:
- **Toluene (A)**: A benzene ring with a methyl group (–CH3) attached.
- **m-Dichlorobenzene (B)**: A benzene ring with two chlorine atoms at the meta positions (1,3-positions).
- **o-Dichlorobenzene (C)**: A benzene ring with two chlorine atoms at the ortho positions (1,2-positions).
- **p-Dichlorobenzene (D)**: A benzene ring with two chlorine atoms at the para positions (1,4-positions).

3. **Analyze Dipole Moments**:
- **Toluene**: The dipole moment is due to the –CH3 group, which is relatively small because the electronegativity difference between carbon and hydrogen is low.
- **m-Dichlorobenzene**: The dipole moments from the two chlorine atoms do not cancel out completely, resulting in a moderate dipole moment.
- **o-Dichlorobenzene**: The dipole moments from the two adjacent chlorine atoms add up, resulting in a higher dipole moment than m-dichlorobenzene.
- **p-Dichlorobenzene**: The dipole moments from the two chlorine atoms are equal and opposite, leading to cancellation of the dipole moments, resulting in a net dipole moment of zero.

4. **Conclusion**:
- The compound with the **highest dipole moment** is **o-Dichlorobenzene (C)** because the dipole moments from the adjacent chlorine atoms add together.
- The compound with the **lowest dipole moment** is **p-Dichlorobenzene (D)** because the dipole moments cancel each other out, resulting in a net dipole moment of zero.

### Final Answer:
- Highest Dipole Moment: **o-Dichlorobenzene (C)**
- Lowest Dipole Moment: **p-Dichlorobenzene (D)**