Question -
Answer -
Conductivity of a solution isdefined as the conductance of a solution of 1 cm in length and area ofcross-section 1 sq. cm. The inverse of resistivity is called conductivity orspecific conductance. It is represented by the symbolκ. If ρ isresistivity, then we can write:
The conductivity of a solution atany given concentration is the conductance (G) of one unit volume ofsolution kept between two platinum electrodes with the unit area ofcross-section and at a distance of unit length.
i.e., 
(Since a =1, l = 1)
Conductivity always decreaseswith a decrease in concentration, both for weak and strong electrolytes. Thisis because the number of ions per unit volume that carry the current in asolution decreases with a decrease in concentration.
Molar conductivity:
Molarconductivity of a solution at a given concentration is the conductance ofvolume V of a solution containing 1 mole of the electrolyte kept between twoelectrodes with the area of cross-section A and distance ofunit length.
Now, l = 1and A = V (volume containing 1 mole of the electrolyte).
Molar conductivity increases witha decrease in concentration. This is because the total volume V of the solutioncontaining one mole of the electrolyte increases on dilution.
Thevariation of 
with
for strong and weak electrolytes is shown in thefollowing plot:
