What is an example of an irreversible physical change?
melting an ice cube
making sawdust
crumpling paper
boiling water

The answer is B. making sawdust.

Because, to make sawdust you have to shred wood and you can't reverse that. Therefore, making sawdust is irreversible.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

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