Answer:
The law of conversion of mass is a scientific law that says that mass or matter can not be created or destroyed like energy but changes its form in a different type of state. So, by the law of conversion of mass, you can say that mass is not disappeared but change in different forms of states of matter like gas, soot, or melted residues of candle and ash of thread.
Due to this, the mass of the solid or waxy state due to burning changes to gas released by burning and residue of wax that will be equal to the mass of the original mass.