Answer:While the pile of ashes and log have similar colors, the change in size, odor, and hardness, and the difference in combustibility indicate that a chemical change has resulted in a substance with a different identity. Furthermore, the ashes cannot be converted back into a log.
A chemical change has occurred because the wood has turned into a substance that can't be changed back to it's original form. The wood has turned to ash, chemical changes are non reversible.