The conductivity of an acid solution depends on the

Analysis

The question asks for the fundamental factors that determine how well an acidic solution conducts electricity. In chemistry, conductivity in an electrolyte (like an acid) is essentially the movement of charged particles (ions) through the solution.

Concept Explanation

To understand conductivity, think of it as "traffic flow" for electricity:

1. The Number of Ions: The more ions (charge carriers) you have in the solution, the more current can be carried. This is why strong acids (which ionize completely) conduct electricity better than weak acids (which only partially ionize).
2. The Mobility of Ions: Even if you have many ions, they must be able to move freely through the solvent to reach the electrodes. Mobility depends on the size of the ion, the viscosity of the solvent, and the temperature.

Conductivity ($\kappa$) is mathematically related to the concentration of ions ($c$) and their molar ionic conductivities ($\lambda$), which represent how fast those specific ions move:

(Where $c$ is concentration, $z$ is charge, $F$ is Faraday's constant, and $u$ is mobility).

Step-by-Step Solution

1. Evaluate Option C: While the amount of ions is important, it is not the only factor. If you have many ions but they are "sluggish" or trapped, conductivity will be low.
2. Evaluate Option B: Similarly, if you have very fast ions but only a tiny amount of them, the total conductivity will be low.
3. Evaluate Option A: This option combines both essential requirements. Conductivity is a product of the number of charge carriers (amount of ions) and how fast they can travel (their mobilities).
4. Evaluate Option D: While temperature does affect mobility, it is a secondary factor that influences the mobility mentioned in Option A, rather than being the primary definition of conductivity itself.

Conclusion

The conductivity of an acid solution is defined by the total concentration of ions available to carry the charge and the speed at which those specific ions can navigate the solution. Therefore, both factors must be considered.

Exam Tip

When you see questions about "conductivity," always look for the "two-part" answer: Quantity (how many) and Quality/Speed (how fast). This logic applies to both Chemistry (electrolytes) and Physics (current electricity).