Which substance is used to remove rust from metal? lye (NaOH) hydrochloric acid (HCl) ammonia (NH_(3)) sulfuric acid (H_(2)SO_(4))'

Rust is a form of corrosion that occurs when iron is exposed to moisture and oxygen. It is a reddish-brown compound called iron(III) oxide. To remove rust, a substance that can dissolve the iron(III) oxide is needed. Among the options provided, hydrochloric acid (HCl) is known to be an effective rust remover. It reacts with the iron(III) oxide to form soluble iron(III) chloride, which can be washed away. The other substances listed do not have the same rust-removing properties as hydrochloric acid. Lye (NaOH) is a strong base and is not typically used to remove rust. Ammonia (NH3) is a weak base and does not have rust-removing properties. Sulfuric acid (H2SO4) is a strong acid, but it is not as commonly used for rust removal as hydrochloric acid. Therefore, the correct answer is hydrochloric acid (HCl).