What is the setup required to demonstrate the effect of salt water on the rusting of iron?

To demonstrate the effect of salt water on the rusting of iron, it is essential to create conditions that allow for both the presence of iron and the corrosive environment provided by salt water. Using iron nails submerged in salt water will enable the observation of rust formation, as salt water accelerates the corrosion process due to its electrolytic properties. An effective control must also be established, which in this case is represented by a setup with iron nails that do not come into contact with water, allowing for a comparison to be made between the rusting conditions.

The use of a control is vital in scientific experiments as it helps to validate the hypothesis regarding the impact of salt water on rusting. By having one set of nails in salt water and another set with no water, the experiment can clearly demonstrate the rate and extent of rusting in the different environments.

This setup is particularly informative because rusting is a type of oxidation that occurs when iron reacts with both oxygen and moisture. Salt enhances this reaction, making it a critical factor to examine in this experiment. Other options either fail to include the necessary corrosive component or do not allow for a comparative analysis to be drawn, thus not effectively addressing the goal of the experiment.