Question

a silver ring reacts with compounds containing sulfur in the air to form silver sulfide, a black substance that makes up the tarnish on the surface of silver objects. to remove the tarnish from the ring, students placed it in a pan lined with aluminum foil and added hot water. baking soda was added to the hot water and stirred. students made observations about the process. which observation of this process provides evidence of a chemical reaction? the liquid solution changed color. the pan was lined with aluminum foil. hot water heated the aluminum foil. the hot water cooled.

Explanation:

To determine evidence of a chemical reaction, we analyze each option:

• "The liquid solution changed color": A color change in the solution during the process (removing tarnish with Al, water, and soap) indicates a new substance is formed, a key sign of a chemical reaction.
• "The pan was lined with aluminum foil": This is a setup detail, not a reaction observation.
• "Hot water heated the aluminum foil": This is heat transfer (physical process), not a chemical reaction.
• "The hot water cooled": Cooling is a physical temperature change, not a chemical reaction.

Answer:

A. The liquid solution changed color