Sodium hydroxide is commonly referred to as?

Sodium hydroxide is commonly referred to as caustic soda. This term highlights its strong alkaline properties and its caustic nature, meaning it can cause severe burns and damage to organic tissue upon contact. Caustic soda is widely used in various industrial applications, such as in the production of soap, the paper industry, and water treatment processes.

The other options do not describe sodium hydroxide accurately. Copper sulfate refers to a different compound, typically used in agriculture and as a fungicide. Bleach usually refers to sodium hypochlorite, which is also an oxidizing agent but serves different purposes, primarily for disinfection and whitening. Hydrochloric acid is a strong acid, contrasting with sodium hydroxide's strong alkaline characteristics. Hence, the characterization of sodium hydroxide as caustic soda is crucial in understanding its chemical identity and applications.