select the best answers.

Question

a collection of gas and dust that forms new stars or is the result of a dying star:
the entire range or electromagnetic waves from low frequency to high frequency:
a chart that plots a star's temperature and brightness, can also tell your special class and color of star:
a huge system of millions or billions of stars, together with gas and dust, all held together by gravity:
a sphere of matter with a density and temperature great enough to cause a nuclear reaction at its center:

galaxy star nebula HR diagram electromagnetic spectrum

Answer 1

a collection of gas and dust that forms new stars or is the result of a dying star: nebula
the entire range of electromagnetic waves from low frequency to high frequency: electromagnetic spectrum
a chart that plots a star's temperature and brightness, can also tell your special class and color of star: HR diagram
a huge system of millions of billions of stars, together with gas and dust, all held together by gravity: galaxy
a sphere of matter with a density and temperature great enough to cause a nuclear reaction at its center: star