In a chemical experiment, 25 g of reactant A reacts completely with 35 g of reactant B to form 50 g of product C and a certain amount of product D. Based on the law of conservation of mass, what is the mass of product D?

When two aqueous solutions react inside a sealed flask and form products, what happens to the total mass of the system?

Consider the following aspects of substances involved in a chemical reaction: A. Physical state of all the substances B. Total number of molecules of all substances C. Number of atoms of each element D. Sum of masses of all atoms of substances According to the law of conservation of mass, which of the above aspects remain unchanged before and after a chemical reaction has taken place?