Question

Assuming that each of the following objects is a typical example of its class, rank them by increasing density.

Answer 1

molecular cloud <interstellar cloud <1 Msun protostar <1 Msun star <intercloud gas

Explanation:

Molecular cloud- They are a variety of interstellar cloud in which molecular hydrogen can sustain themselves. They have a very low temperature ranging from -440 to -370 degrees Fahrenheit or between 10 to 50 Kelvin. Owing to their extremely low temperature, they appear mostly dark when viewed through telescopes.

Interstellar cloud- They are a congregation of a large number of interstellar gases, dust and plasma in any galaxy or universe. They have varying temperature depending on their proximity to a star. E.g. Neutral hydrogen atom clouds have a temperature of around just 100 Kelvin while those in the near vicinity of a star have temperatures as high as 10,000 Kelvin.

1 Msun star- These stars have temperature anywhere between 5300 and 6000 Kelvin. The main source of such high surface temperature is nuclear fusion process where elemental hydrogen molecules are fused to form helium molecules.  

1 Msun protostar- protostar is rather a young star which is still in formation phase (i.e. gathering mass from the parent molecular cloud). They have temperature anywhere between 2000-3000 kelvin and are accompanied by dust usually.

Intercloud gas- These are the remainder gases that are spread throughout the interstellar space. This Intercloud gas is divided into warm intercloud medium and extremely hot coronal gas with temperatures comparing to Sun’s corona. Warm intercloud forms the dominant part of intercloud gas with a temperature around 8000 Kelvin.