Introduction:
When studying the relationship between concentration and conductance, it is common to take the square root of concentration while finding its variation with conductance. This practice is based on the concept of the relationship between concentration and electrical conductivity in a solution.

Explanation:
1. Electrical Conductivity:
Electrical conductivity is a measure of a substance's ability to conduct an electric current. In the case of solutions, it depends on the presence of ions and their mobility in the solution. Ionic compounds, when dissolved in a solvent, dissociate into ions, which are responsible for the conducting properties of the solution.

2. Conductance and Concentration:
Conductance is the reciprocal of resistance and is directly proportional to the concentration of ions in a solution. As the concentration of ions increases, the conductance of the solution also increases. This relationship is described by the equation:

Conductance (G) = κ × A / d

Where G is the conductance, κ is the specific conductance or conductivity, A is the area, and d is the distance between the electrodes.

3. Relationship between Conductance and Concentration:
The conductance of a solution is directly proportional to the concentration of ions present. However, the relationship is not linear; it follows a square root relationship. This is because the number of ions available for conduction increases with the square root of concentration.

4. Ion-Ion Interactions:
In a solution, ions interact with each other through various forces such as electrostatic attraction or repulsion. These interactions affect the mobility of ions and their ability to conduct electricity. The presence of other ions can hinder the movement of ions and reduce the overall conductance of the solution.

5. Taking the Square Root:
Taking the square root of concentration while finding its variation with conductance helps to account for the non-linear relationship between concentration and conductance. By doing so, the effects of ion-ion interactions and other factors that affect the mobility of ions are better represented in the relationship.

Conclusion:
In summary, taking the square root of concentration while finding its variation with conductance is based on the square root relationship between the number of ions available for conduction and concentration. This practice helps to account for ion-ion interactions and other factors that affect the mobility of ions in a solution.