Which process is a chemical change? breaking of glass formation of frost magnetization of an iron nail loss of atmospheric ozone

The process that is a chemical change is the loss of atmospheric ozone. A chemical change happens when the substance changes its physical state and composition resulting from a chemical reaction. The loss of the ozone undergoes a chemical reaction.

 loss of atmospheric ozone

Explanation: Chemical change is a change which result in a change in chemical composition of reactants.

Physical change is a change which do not result in a change in chemical composition of reactants.

a) Breaking of glass would only lead to conversion of large piece of glass to small pieces and there is no change in chemical composition.

b) Formation of frost results when water vapor in the atmosphere gets cold enough to freeze. Thus there is no change in chemical composition.

c) Magnetization of an iron nail is due to the alignment of dipoles in one particular direction and thus there is no chemical change.

d) Loss of atmospheric ozone results when free radicals combine with ozone to form molecular oxygen. Thus there is a change in chemical composition and hence this is  a chemical change.