Hydrochloric acid is used to clean metals. The acid reacts with the oxide layer on the surface of the metal, forming a salt and water. Which word best describes the metal oxide? A) alloy b) base c) element d) indicator

Answer;

A base

Explanation; A base is a substance that reacts with an acid to form salt and water as the only products, in a reaction called neutralization reaction. A base turns red litmus paper blue while an acid turns blue litmus paper red. HCl is an acid that reacts with a base to form salt and water as the only product, during neutralization reactions. During the cleaning of metals it reacts with oxide layers on the surfaces of metal forming salt and water.