When a piece of zinc metal is placed in hydrochloric acid, a gas is produced. A. nitrogen B. hydrogen C. carbon dioxide D. oxygen

The correct answer is B. Hydrogen.

When a piece of zinc metal is placed in hydrochloric acid, a gas is produced. This gas is hydrogen. The reaction is as follows:

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

Zinc metal reacts with hydrochloric acid to produce zinc chloride and hydrogen gas. The hydrogen gas is produced as bubbles that rise to the surface of the solution.

The other options are incorrect. Nitrogen is not produced in this reaction. Carbon dioxide is produced when carbon-containing materials react with acids, but zinc does not contain carbon. Oxygen is not produced in this reaction.

I hope this helps!