Question

The one which decreases with dilution is:
A. Molar conductivity
B. Conductance
C. Specific conductance
D. None of these

Answer 1

A concentrated solution has a lot of ions dissociated into it, which help in the passage of current. Whereas in a dilute solution, the number of charge carriers i.e ions are less, so less current is passed. It faces high resistance.

Complete Solution :
In order to answer our question, we need to get familiar with all the terms mentioned in the question.
Conductance: Conductance is the measure of the ease with which current flows through the conductor. It is actually the inverse of resistance. It is denoted by G, where $G=\dfrac{1}{R}$, R being the resistance. Units of conductance is ${{\Omega }^{-1}}$ and it is expressed in Siemens denoted by S.

Molar conductivity: The conductivity of a metallic conductor has a definite value at a given temperature. It is due to the fact that conductivity of a solution is directly associated with the presence of ions. In case of electrolytic solutions, the more appropriate term “molar conductivity” is used, which includes both the conductivity and concentration of the solution. Molar conductivity is defined as the conductance of a solution kept between the electrodes at unit distance apart and having an area of cross section that is sufficient and big in order to fit in itself the volume of the solution that contains one mole of the electrolyte. It is denoted by the symbol ${{\wedge }_{m}}$.

Specific conductance: Specific conductance is also called conductivity. It is the reciprocal of resistance. It may also be defined as the conductance of one centimetre cube of the conductor. It is generally denoted by the Greek letter Kappa ($\kappa$).
$\kappa =\dfrac{1}{\rho }=\dfrac{1}{R}(\dfrac{l}{a})$, where l and a are length and area respectively. Unit of conductivity is ${{\Omega }^{-1}}c{{m}^{-1}}$.
Now, in a concentrated solution, there will be more ions. So, current carrying capacity will be more as ions are the majority charge carriers. Whereas in dilute solution, the concentration of ions is less, so the current passed is less. Hence the conductivity or specific conductance decreases.
So, the correct answer is “Option C”.

Note: The factors on which electrolytic conduction are affected are:
A. Nature of electrolyte
B. Size of anions and their solvation
C. Nature of solvent and its viscosity
D. Concentration of solution
E. Temperature