How can a simple salt bridge be prepared?

A simple salt bridge can be prepared effectively by dipping filter paper into a salt solution. This method involves soaking the filter paper in a solution containing an electrolyte, such as potassium chloride (KCl) or sodium sulfate (Na2SO4). Once the filter paper is saturated with the salt solution, it can act as a bridge between two half-cells in an electrochemical cell.

The key function of the salt bridge is to maintain electrical neutrality in the half-cells by allowing ions to flow between them. The saturated salt solution in the filter paper provides ions that can migrate to balance out the charges that build up as the electrochemical reactions occur in the cells. This is crucial for the functioning of the electrochemical cell, allowing a continuous flow of current and promoting the overall reaction.

Using a piece of glass, mixing two metals, or pouring water into a container does not create the necessary conditions for a salt bridge. Glass does not conduct ions effectively, mixing metals does not introduce an electrolyte solution, and pouring water alone lacks the ionic components required for a functioning salt bridge. Thus, the correct option highlights a practical method for establishing an ionic connection between two electrochemical systems.