State the type of chemical reaction when zinc metal reacts with hydrochloric acid to produce hydrogen gas.

Step-by-step solution

1. Write the reactants and products: $\text{Zn}+2\text{HCl}\to {\text{ZnCl}}_2+{\text{H}}_2$.
2. Observe that a metal (Zn) replaces hydrogen in the acid.
3. When an element displaces another from its compound, the reaction is a single displacement (or replacement) reaction.
4. Hence the reaction type is single displacement.

Concept tested: Classification of reactions

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