Conductivity of a solution is directly proportional to:

Options

A. Dilution
B. Number of ions
C. Current density
D. Volume of the solution

Answer

To solve the question regarding the conductivity of a solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Conductivity**:
Conductivity (κ) of a solution is a measure of its ability to conduct electric current. It is directly related to the presence of charged particles (ions) in the solution.

2. **Formula for Resistance**:
The resistance (R) of a solution can be expressed using the formula:
\[ R = \frac{\rho l}{A} \]
where:
- \( R \) = resistance,
- \( \rho \) = resistivity,
- \( l \) = length of the conductor,
- \( A \) = cross-sectional area.

3. **Relationship Between Conductivity and Resistivity**:
Conductivity (κ) is the reciprocal of resistivity (ρ):
\[ κ = \frac{1}{\rho} \]
Therefore, we can express resistance in terms of conductivity:
\[ R = \frac{1}{κ} \cdot \frac{l}{A} \]

4. **Units of Conductivity**:
The unit of conductivity is Siemens per centimeter (S/cm), which can also be expressed as ohm inverse centimeter inverse (Ω⁻¹ cm⁻¹).

5. **Factors Affecting Conductivity**:
The conductivity of a solution is directly proportional to the number of ions present in the solution. More ions lead to higher conductivity because they facilitate the flow of electric current.

6. **Conclusion**:
Therefore, we conclude that the conductivity of a solution is directly proportional to the number of ions per unit volume in the solution.

### Final Answer:
The conductivity of a solution is directly proportional to the number of ions per unit volume.

---