Final answer
Physical changes in a substance can be reversed and do not affect its identity whereas chemical changes are irreversible and transform a substance into a new one.
Step-by-step explanation:
Physical changes such as the change in size, shape, or volume do not involve a change in the identity of a substance. They can typically be undone or reversed and the original substance can be recovered; thus they are marked by 'P'.
Chemical changes, however, result in a substance changing into a new one, with new properties. This is often signaled by a change in color, gas being produced and given off, or energy being released or absorbed. These changes are irreversible under normal conditions meaning the original substance cannot be recovered; this is labelled as 'C'.
Learn more about Chemical and Physical Changes