What gas is released during the reaction of an acid with a metal?

When an acid reacts with a metal, one of the products commonly formed is hydrogen gas. This reaction typically involves a metal displacing hydrogen from the acid. For instance, in the case of hydrochloric acid reacting with zinc, the equation can be represented as:

[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \uparrow ]

In this reaction, zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen gas. The release of hydrogen is observed as bubbles forming, indicating that gas is being produced.

Other gases mentioned in the choices would not be produced in this specific reaction involving acids and metals. For example, carbon dioxide might be released during reactions involving carbonates and acids, but it does not occur when metals react with acids. Oxygen, while important in other chemical reactions and processes, is not a product of this particular metal and acid interaction. Nitrogen is typically not involved in reactions between metals and acids either, as it is primarily a stable, inert gas at room temperature and does not form in acid-metal reactions.

Thus, hydrogen is the gas released during the reaction of an acid with a metal, validating the choice as the correct