A characteristic of a pure substance that can be observed without changing it into another substance

Which of the following is true about the speed of light? it depends on the wavelength.

What is the mass of 0.750 mole of aluminum oxide, al2o3?

Can anyone explain 1. review your spectrometry data and use the known elements to identify the star's composition. which unknown elements make up this star? justify your element selections. 2. in parts i and ii of the lab, what happened to the electrons of each element to produce the different colors of light? explain your answers using important terms from the lesson and information provided in the laboratory. 3. stars composed of heavier (more massive) elements are often slightly older than stars made predominantly from hydrogen and helium. based on your data, is the newly discovered star a younger star? explain your answer.