Why is mass important?
First it is regarded as fundamental quantity. Secondly in almost all calculations of physics and chemistry it is an important parameter
There is no reason why mass is not important. The reason for saying that is that mass is very very very important for a lot of reasons. Everything has mass, so mass is part of everything that is important. Only ideas do not have mass, but a lot of people think that a lot of ideas have weight. Also without mass gravity would have nothing to pull on and we would not know that gravity…
The law of conservation of mass is so important in chemistry because it governs every chemical reaction. If a chemical reaction occurs, there will be equal mass as what the starting mass was. It will either be all products, all reactants or a combination of the afermentioned. Even if some energy is released in heat or light, it technically still has a mass that is equal to the starting (orginal) mass.
It is important to know about the mass of a star because the mass affects what happens in the later stages in its life cycle. Stars with the highest mass have the shortest life because they use up their supply of fuel rapidly. Stars with very low mass have the longest life, just like our sun, because it takes a very long time to use up their supply of fuel.