NiCl₂ and NaOH are both electrolytes, which means that they dissociate in water to form ions, which are charged particles that can conduct electricity.
When NiCl₂ is dissolved in water, it dissociates into Ni²⁺ ions and Cl⁻ ions. The conductivity of a dilute solution of NiCl₂ is relatively low because there are fewer ions present in the solution, and thus fewer ions available to conduct electricity.
When the concentration of NiCl₂ is increased, the conductivity of the solution also increases. This is because as the concentration of the solution increases, there are more ions present in the solution, which results in a greater ability to conduct electricity.
Similarly, when NaOH is dissolved in water, it dissociates into Na⁺ ions and OH⁻ ions. As with NiCl₂, the conductivity of a dilute solution of NaOH is relatively low because there are fewer ions present in the solution. As the concentration of NaOH is increased, the conductivity of the solution increases because there are more ions present in the solution.
In summary, the conductivity of dilute solutions of NiCl₂ and NaOH is low because there are fewer ions present in the solution. As the concentration of these solutions increases, the conductivity increases because there are more ions present in the solution.