The ash produced by the burning paper has much less mass than the mass of the original paper. Was mass conserved during this change? Explain your answer.
Mass was not conserved during this change. When paper burns, oxygen from the air combines with carbon and hydrogen from the paper in a chemical reaction to produce CO2 and water vapour. These waft away after the burning, just like smoke. Therefore, the paper has a lighter mass, because some of the mass it held before (from the carbon and hydrogen) has been lost.
