Question

which process is a sign of a chemical change?
a melting block of ice leaves a large puddle
a cloud quickly changes shape when blown by wind
a plaster statue breaks when it falls onto the floor
a rotting potato gives off a bad smell

Explanation:

A chemical change results in the formation of new substances. Rotting of a potato is a chemical change as it involves decomposition and formation of new compounds (which give off the bad smell). Melting of ice is a physical change (change of state from solid to liquid). Breaking of a plaster statue is a physical change (change in shape). A cloud changing shape when blown by wind is a physical change (change in shape).

Answer:

A rotting potato gives off a bad smell.