Which gas is given off when dilute hydrochloric acid reacts with magnesium?

Answer and explanation

Correct answer: C. Hydrogen

Acid + reactive metal gives a salt and hydrogen; here magnesium chloride and hydrogen.
Answer: Hydrogen.
Why not the others: Oxygen: oxygen is not produced by an acid and a metal. Carbon dioxide: that needs a carbonate. Chlorine: the chloride ions stay in solution.

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