The law of conservation of matter states that matter cannot be created or destroyed in a chemical reaction. It can only change forms or rearrange its composition.
In the given chemical equation, Al-2o3 + Al + O2, the equation does not demonstrate the law of conservation of matter because the number of aluminum (Al) atoms on the left side (2) is not equal to the number of aluminum (Al) atoms on the right side (1). The equation should be balanced in order to obey the law of conservation of matter.