Which of the following are chemical changes? W. The evaporation of water X. Burning of wood

Which of the following are chemical changes?

W. The evaporation of water

X. Burning of wood Y. Dissolution of sugar Z. Souring of milk

Solution: Chemical changes alter the identity of the substance. A reaction always leads to a chemical change. Physical changes, on the other hand, do not change the identity of a substance. Phase changes such as going from solid to liquid are most common physical changes.

Which of the answer choices represent a reaction? That must be X burning of wood and Z souring of milk.