Analyze Property Changes Practice Test

A student heats a small piece of candle wax in a metal spoon.

Before heating: wax is a hard, white solid at 21°C with a smooth surface.

After heating for 2 minutes: wax becomes a clear liquid at 55°C and looks shiny; no bubbles or smoke are seen.

Based on these observations, what type of change occurred?

A student drops a small piece of shiny magnesium ribbon (solid, silver-gray, 20°C) into a cup of clear hydrochloric acid (liquid, colorless, 20°C). After 30 seconds, the magnesium piece is much smaller, many bubbles rise from its surface, and the cup feels warmer (temperature increases to 28°C).

Which property changed in a way that most strongly suggests the substances reacted?