Most metals are solid at room temperature, malleable, ductile, good conductors of heat and electricity, and react in acids to produce hydrogen gas. which of the properties mentioned is a chemical property?

The answer to your question is:   "react with acids to produce hydrogen gas"

Explanation:

Chemicals properties of matter: are properties that can be measured if there is a chemical change or chemical reaction.

Examples of chemical reactions:

Reactivity

Toxicity

Coordination number

Flammability

Of the properties listed, the only that implies a reaction is "react with acids to produce hydrogen gas"