Karat gold, sterling silver and some gems can be attacked by which substance?

• A. Hydrogen peroxide
• B. Chlorine
• C. Acid rain
• D. Ozone

Answer: (B)

Chlorine is a strong oxidizing agent that readily reacts with metals and with many gemstone materials. Karat gold is an alloy, usually with copper and other metals; chlorine can form metal chlorides on the surface, leading to corrosion, pitting, and loss of the alloy’s strength and luster. Sterling silver also contains copper, so chlorine exposure creates silver chlorides, causing tarnish and surface degradation. For gems, chlorine can attack porous or chemically sensitive stones or remove protective surface coatings, resulting in etching, color changes, or a dull appearance. Because of these effects, chlorine exposure—such as from swimming pools, household bleach, or strong cleaners—should be avoided for jewelry.