Complex sentence: In relation to Lavoisier's law of conservation of matter, which states that matter can be neither created nor destroyed only altered, the combustion or burning of a substance causes a chemical change, but does not decrease the mass of the original matter.
Split into simpler sentences: In relation to Lavoisier's law of conservation of matter, which states that matter can be neither created nor destroyed only altered. Means that the combustion or burning of a substance causes a chemical change, but does not decrease the mass of the original matter.