What is produced when an acid reacts with a metal?

When an acid reacts with a metal, one of the primary products formed is hydrogen gas. This occurs because the acid donates protons (H⁺ ions) to the metal, resulting in a chemical reaction where the metal displaces the hydrogen ions from the acid. The metal typically combines with the anion of the acid to form a salt.

For example, if hydrochloric acid (HCl) reacts with zinc (Zn), the reaction produces zinc chloride (ZnCl₂) and hydrogen gas (H₂). This essential reaction showcases how metals can react with acids to yield a salt and hydrogen, emphasizing the release of hydrogen as a gas. Thus, the formation of salt and hydrogen is a characteristic outcome of such reactions, making the correct choice the one that highlights these products.

The other options present incorrect combinations that do not typically result from metal-acid reactions. For instance, while acids can produce water in neutralization reactions (with bases), they do not produce water when reacting with metals. Similarly, while oxygen is sometimes involved in reactions, it is not a product of metal-acid interactions, and the production of sugar is unrelated to these types of chemical reactions.