which substance combines with iron in the presence of water to form rust?
Oxygen
acid
nitrogen
carbon dioxide
The substance that combines with iron in the presence of water to form rust is oxygen.
The process most likely responsible for the formation of limestone caves is carbonation.
which process is most likely responsible for the formation of limestone caves?
oxidation
abrasion
carbonation
hydrolysis
Oxygen is the substance that combines with iron in the presence of water to form rust.
The substance that combines with iron in the presence of water to form rust is oxygen. Rust is an iron oxide compound that is formed when iron reacts with oxygen and water. Specifically, the oxygen in the air or dissolved in water reacts with the iron, oxidizing it and leading to the formation of rust.
To arrive at this answer, you can recall the process of rust formation or conduct a simple experiment. Here's a basic experiment you can try to see rust formation in action:
1. Take a small piece of iron or steel, such as a nail or paperclip.
2. Dip the iron object into a cup of water, making sure it is fully submerged.
3. Leave the iron in the water for a few hours or overnight, ensuring that it remains in contact with the water.
4. After some time, you will notice a reddish-brown substance forming on the surface of the iron object. This is rust.
5. By recognizing that rust forms when iron is exposed to water and air, you can conclude that oxygen is the substance that combines with iron to form rust.
Further research or experimentation can be done to explore the influence of acid, nitrogen, or carbon dioxide on rust formation. However, oxygen is the primary substance involved in the process.