Salt compounds are formed from an acid by replacing which part with a metal?

• A. Hydrogen
• B. Oxygen
• C. Carbon
• D. Nitrogen

Answer: (A)

The key idea is that salts form when a metal takes the place of hydrogen in an acid. In an acid, hydrogen is the part that can be released as a gas when a reactive metal is added. When the metal reacts, it replaces that hydrogen, and the remaining part of the acid (the anion) bonds with the metal to make a salt. For example, sodium reacting with hydrochloric acid replaces the hydrogen to give sodium chloride (NaCl) and hydrogen gas. The same idea applies with other acids, where the metal ends up paired with the acid’s remaining anion to form the salt. The other elements like oxygen, carbon, or nitrogen aren’t the part that’s replaced by the metal in this process.