The one which decreases with dilution is :

Options

A. Molar conductance
B. Conductance
C. Specific conductance
D. Equivalent conductance

Explanation

To solve the question, "The one which decreases with dilution is:", we need to understand the behavior of different types of conductance in an electrolyte solution when it is diluted.

### Step-by-Step Solution:

1. **Understanding Conductance**:
- Conductance (G) is the ability of a solution to conduct electricity. It depends on the number of ions present in the solution.

2. **Types of Conductance**:
- **Specific Conductance (κ)**: This is the conductance of a solution per unit length and is dependent on the concentration of ions in the solution.
- **Molar Conductance (Λm)**: This is the conductance of a solution containing one mole of electrolyte in a given volume of solution.
- **Equivalent Conductance (Λeq)**: This is the conductance of a solution containing one equivalent of electrolyte in a given volume of solution.

3. **Effect of Dilution**:
- When a solution is diluted, the total number of ions in the solution increases because the same number of ions is now spread over a larger volume.
- As a result, the molar conductance and equivalent conductance increase with dilution due to the increased mobility of ions and reduced ionic interactions.

4. **Specific Conductance Behavior**:
- However, specific conductance (κ) decreases with dilution. This is because specific conductance is defined as the conductance of a solution per unit volume. When we dilute the solution, the concentration of ions per unit volume decreases, leading to a decrease in specific conductance.

5. **Conclusion**:
- Therefore, the one which decreases with dilution is **specific conductance (κ)**.

### Final Answer:
The one which decreases with dilution is **specific conductance (κ)**.