How does a balanced chemical equation show that mass is never lost or gained in a chemical reaction

On your wedding day your lover gives you a gold ring of mass 3.67 g. 48 years later its mass is 3.44 g. on the average how many atoms were abrated from the ring during each second of your marriage? the atomic mass of gold is 197 u. don't enter units

The is a pea sized structure in the brain that is involved in many aspects of motivation, including sex, aggression,and hunger

The momentum of a car travelinv in a straight line at 20 m/s is 24,500kg·m/s. what is the cars mass?