How does the precision of each instrument used in the lab affect the number of significant digits used to evaluate density?

How many moles of potassium hydroxide are needed to completely react with 2.94 moles of aluminum sulfate according to the following equation:

What is the best describtion of the side of the moon that faces earth?

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.