Which objects should be included within the system in order to make an energy analysis as easy as possible

What is created when solids,liquids,an gases mix with one another

Idon’t quite understand this problem

Aspectroscope breaks light up into its colors, allowing scientists to analyze light from the solar system and universe. by studying the spectral line patterns, widths, strengths and positions, scientists can determine the speed, position, and of celestial bodies. a) age b) origin c) rotation d) temperature