Question

a piece of zinc metal is dropped in dilute solution of hydrochloric acid. (A) which gas is liberated when a metal reacts with acid

Answer 1

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When zinc metal is dropped in dilute HCl the Hydrogen gas is released. The overall reaction can be written as

Zn + HCl. -----------> ZnCl2 + H2

when a metal reacts with acid the release of Hydrogen takes place.

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Answer 2

Zn+ 2HCl------ H^2+ ZnCl^2
hydrogen gas is liberated when the metal zinc is reacted with HCl