Law of Conservation of Mass — Prelims Questions

When 10.0 g of calcium carbonate ($CaCO_3$) is heated in a closed container, it decomposes to form calcium oxide ($CaO$) and carbon dioxide ($CO_2$). If 5.6 g of calcium oxide is produced, what is the mass of carbon dioxide formed?

Which of the following statements is NOT consistent with the Law of Conservation of Mass?

A student burns 2.4 g of magnesium ribbon in an open crucible. After the reaction, 4.0 g of magnesium oxide is formed. What is the mass of oxygen from the air that reacted with the magnesium?

In an experiment, 12.0 g of element X reacts completely with 16.0 g of element Y to form a compound XY. What is the total mass of the compound XY formed?

Which of the following scenarios best demonstrates the Law of Conservation of Mass?

When 2.0 g of hydrogen gas reacts with 16.0 g of oxygen gas to form water, what is the total mass of water formed, assuming complete reaction?