0 Which is not a chemical change? A Iron combines with oxygen to form
rust.
B Wax melts as it absorbs heat from a
flame.
C Pure sodium explodes when dropped
in water.
D Glucose molecules are produced in a
plant leaf.

B, wax melting

Explanation:

When wax melts, the form of matter is the only thing that changes. Wax in this case goes from a solid to a liquid, and this process can be reversed when it cools. Hence labeling it a physical change instead.