Question

Electrical conductance due to all the ions in $1\ \text{cm}^3$ of given solution is called as

• A. Molar conductivity
• B. Resistivity
• C. Conductivity
• D. Electrical conductance

Hint:

To remember this clearly, think of conductivity ($\kappa$) as "volume-specific conductance" ($1\ \text{cm}^3$) and molar conductivity ($\Lambda_m$) as "amount-specific conductance" ($1\ \text{mole}$).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the specific electrochemical term that defines the electrical conductance of a solution contained within a unit volume cube ($1\ \text{cm}^3$).

Step 2: Key Formula or Approach:
Conductance ($G$) is related to the geometry of the cell by the relation: $$G = \kappa \frac{A}{l}$$ where $\kappa$ is the conductivity, $A$ is the cross-sectional area of the electrodes, and $l$ is the distance separating them. When both $A = 1\ \text{cm}^2$ and $l = 1\ \text{cm}$, the total volume enclosed is exactly $1\ \text{cm}^3$, making $G = \kappa$.

Step 3: Detailed Explanation:
Let's analyze the precise physical definitions of the given terms:

Conductivity ($\kappa$): It is explicitly defined as the individual conductance of a solution kept between two parallel electrodes of unit cross-sectional area separated by a unit length distance. This corresponds to a standard solution block volume of exactly $1\ \text{cm}^3$ (or $1\ \text{m}^3$ in SI units).

Molar conductivity ($\Lambda_m$): This is the electrolytic conductance of a volume of solution containing exactly one mole of dissolved electrolyte.

Resistivity ($\rho$): This is the fundamental material property that opposes electrical flow; it represents the electrical resistance of a unit volume. Therefore, the conductance of $1\ \text{cm}^3$ of a solution is termed its conductivity (historically referred to as specific conductance).

Step 4: Final Answer:
The given definition describes conductivity, which corresponds to option (C).