Question

a student lights a candle, creating a flame. over time, heat from the flame causes some candle wax to melt. which statement describes the changes that occurred?
a the flame indicates a physical change occurred, and the wax melting indicates a chemical change.
b the flame indicates a chemical change occurred, and the wax melting indicates a physical change.
c both the flame and the wax melting are indicators of chemical changes.
d both the flame and the wax melting are indicators of physical changes.

Explanation:

• Chemical change: A chemical change results in the formation of new substances. When a candle burns (creating a flame), wax reacts with oxygen to produce carbon dioxide, water vapor, etc. So, the flame indicates a chemical change.
• Physical change: A physical change does not create new substances. Wax melting is a phase change (from solid to liquid). The chemical composition of wax remains the same. So, wax melting is a physical change.

Answer:

B. The flame indicates a chemical change occurred, and the wax melting indicates a physical change.