Question

which substance is used to remove rust from metal?
lye (naoh)
hydrochloric acid (hcl)
ammonia (nh3)
sulfuric acid (h2so4)

Explanation:

Rust is iron - oxide. Acids react with metal oxides to form salts and water. Hydrochloric acid is commonly used for rust removal as it can effectively dissolve rust. Lye is a base and does not react with rust in a way to remove it. Ammonia is a weak base and not suitable for rust removal. While sulfuric acid can react with rust, it is a very strong acid and more dangerous to handle compared to hydrochloric acid for general rust - removal purposes.

Answer:

B. hydrochloric acid (HCl)