Final answer:
Sodium nitrite is best used on ferrous metals as a corrosion inhibitor to protect them from rusting.
Step-by-step explanation:
Sodium nitrite is best used on ferrous metals. Sodium nitrite is an ionic compound that can serve as a corrosion inhibitor for ferrous metals such as iron and steel. It helps in protecting these metals from rusting, which is especially important in various industries where these metals are exposed to moisture and need to maintain their integrity for safety and functionality. Although sodium nitrite can be used in preserving meats due to its antimicrobial properties, in the context of metals, its application is mainly associated with ferrous metals.