A reaction occurs between two liquid substances in a sealed container. Based on the law of conservation of mass, what will happen to the mass of the sealed container and its contents overall?

This choice incorrectly suggests that producing a gas would lead to a decrease in mass. While gases can escape from an open system, a sealed container retains all products of the reaction, including gases. Therefore, the mass will not decrease; it will remain constant.

This option implies that the formation of a solid from the reaction would somehow increase the mass of the system. However, the mass of the reactants and products must balance according to the conservation of mass, meaning that the solid produced does not add to the total mass of the closed system.

Similar to option B, this choice incorrectly assumes that producing a liquid will increase the total mass. In reality, the mass remains unchanged, as the mass of the liquid is accounted for in the original reactants. All changes in state do not affect the overall mass in a sealed container.