Which relation is correct?

Options

A. Molar conductance = conductivity `xx` concentration
B. Equivalent conductance `= ("Conductivity")/("Volume")`
C. Cell constant `=("Conductivity")/("Conductance")`
D. Conductance = specific conductivity `xx` cell constant

Answer

To determine which relation is correct among the given options, we will analyze each relation step by step:

1. **Understanding Molar Conductance**:
- Molar conductance (Λm) is defined as the conductivity (κ) multiplied by the volume concentration (C) of the solution.
- The correct formula is:
\[ \Lambda_m = \frac{\kappa}{C} \]
- Therefore, the relation "Molar conductance is equal to conductivity into concentration" is incorrect.

**Hint**: Remember that molar conductance is inversely related to concentration.

2. **Understanding Equivalent Conductance**:
- Equivalent conductance (Λeq) is defined as the conductivity (κ) divided by the volume concentration of equivalents (Ceq).
- The correct formula is:
\[ \Lambda_{eq} = \frac{\kappa}{C_{eq}} \]
- Since we need to consider the valency factor in equivalent conductance, the statement "Equivalent conductance is equal to conductivity by volume" is also incorrect.

**Hint**: Equivalent conductance involves the valency factor, so it cannot be simplified to just conductivity divided by volume.

3. **Understanding Cell Constant**:
- The cell constant (K) is defined as the ratio of conductivity (κ) to conductance (G).
- The correct relation is:
\[ K = \frac{\kappa}{G} \]
- Therefore, the statement "Cell constant is equal to conductivity by conductance" is correct.

**Hint**: The cell constant relates conductivity to how much current flows through the cell.

4. **Understanding Conductance**:
- Conductance (G) is defined as the reciprocal of resistance (R) and can also be expressed in terms of specific conductivity (κ) and the cell constant (K):
\[ G = K \cdot \kappa \]
- Therefore, the statement "Conductance is equal to specific conductivity into cell constant" is correct.

**Hint**: Conductance is a measure of how easily electricity can flow through a solution.

5. **Conclusion**:
- After analyzing all the relations, we find that the only correct relation is the third one: "Cell constant is equal to conductivity by conductance".

**Final Answer**: The correct relation is the third one: "Cell constant is equals to conductivity by conductance".