Question

Why does the conductivity of solution decreases with dilution?

Answer 1

The conductivity of a solution is directly proportional to number of ions present in a unit volume of the solution because current is carried forward by the ions. With dilution number of ions in unit volume decreases so that conductivity also decreases. Hence with dilution conductivity decreases.

Answer 2

Conductivity of a solution is the conductance of ions present in a unit volume of the solution. On dilution, the number of ions per unit volume decreases. Hence the conductivity decreases.