Which statement about displacement reactions is true?

• A. Displacement reactions occur only in gases.
• B. A metal can replace another metal in a compound if it is more reactive.
• C. Displacement reactions always produce a precipitate.
• D. Displacement reactions require chlorides.

Answer: (B)

In a single-displacement reaction, a more reactive metal can push a less reactive metal out of a compound. The firing rule is set by the reactivity series: if a metal sits higher in the series than the metal in the compound, it can replace it.

This statement is the best because it captures that driving force—the relative reactivity. For example, when zinc metal is added to copper(II) sulfate solution, zinc, being more reactive, displaces copper from the compound, giving zinc sulfate in solution and depositing copper metal. That shows how reactivity, not state or the need for a specific salt, governs the outcome.

Displacement reactions don’t have to occur in gases; they happen in aqueous solutions (and often in molten salts) as ions and metal atoms interact. They also don’t always produce a precipitate—depends on the solubility of the products. If the displaced metal forms a soluble salt, you won’t see a solid. And these reactions don’t require chlorides specifically; many different metal salts can participate, with the reaction decided by the relative reactivities of the metals involved.