Which statement is true about gas production when acids react with listed substances?

Which statement is true about gas production when acids react with listed substances?

• A. Hydrogen is produced when zinc reacts with hydrochloric acid
• B. Oxygen is produced when zinc reacts with hydrochloric acid
• C. Hydrogen is produced when calcium carbonate reacts with hydrochloric acid
• D. Carbon dioxide is produced when zinc reacts with hydrochloric acid

Answer: (A)

Gas production in acid reactions depends on what the acid reacts with. When a metal meets a strong acid, hydrogen gas is typically released. For zinc and hydrochloric acid, the reaction is Zn + 2HCl → ZnCl2 + H2, so hydrogen gas is evolved. Calcium carbonate reacting with hydrochloric acid yields carbon dioxide and water (CaCO3 + 2HCl → CaCl2 + CO2 + H2O), so the gas produced is CO2, not hydrogen. Oxygen gas isn’t generated in these common acid–metal or acid–carbonate reactions. So the statement that hydrogen is produced when zinc reacts with hydrochloric acid is the correct one.

Gas production in acid reactions depends on what the acid reacts with. When a metal meets a strong acid, hydrogen gas is typically released. For zinc and hydrochloric acid, the reaction is Zn + 2HCl → ZnCl2 + H2, so hydrogen gas is evolved.

Calcium carbonate reacting with hydrochloric acid yields carbon dioxide and water (CaCO3 + 2HCl → CaCl2 + CO2 + H2O), so the gas produced is CO2, not hydrogen. Oxygen gas isn’t generated in these common acid–metal or acid–carbonate reactions.

So the statement that hydrogen is produced when zinc reacts with hydrochloric acid is the correct one.