What happens to marble when subjected to heat?

• A. Turns to lava
• B. Turns to chalk
• C. Turns to dust
• D. Turns to glass

Answer: (B)

The substance in marble is calcium carbonate. When heated, calcium carbonate undergoes calcination: it breaks down and releases carbon dioxide, leaving behind calcium oxide. If that residue then comes into contact with moisture in the air, it hydrates to calcium hydroxide, which is a white, chalky material. In many fire-related observations, this chalky, powdery residue is the most noticeable change, so describing the result as turning to chalk aligns with what you’d see as the material transforms under heat and moisture. The other options don’t match the typical outcome: marble won’t melt into lava, it doesn’t simply become a fine, inert powder as a primary product, and turning into glass would require conditions that melt the rock outright, which isn’t the normal result of heating marble in most fire scenarios.