Question

How are these four stars ranked in decreasing order of atmospheric Density: giants, supergiant, white dwarfs, main sequence.

Answer 1

Hint: The density of air or atmospheric density is mass per unit volume of earth’s atmosphere. the bigger the diameter the lesser Will be the density. The bigger giant planets are mostly gas giants and most of them even do not have any solid surfaces.

Complete answer:
The decreasing order of the four stars is, dwarfs have the Greatest density as they have collapsed inward while main Sequence is in the middle of the order, giants & supergiant have the greatest spherical diameter so their density is Very less.
Giants & supergiant stars: They are much larger stars than the corresponding main Sequence stars. They have high brightness & larger radii for their masses. They are very massive, that's why their Density is very less.
White dwarfs: Hot stars are called white dwarfs but white dwarf does not Undergo fusion reaction as it has no source of energy. So, it is also known as a degenerate dwarf. its mass is Comparable to the sun & volume is comparable to the Earth.
Main sequence: These stars fuse hydrogen atoms to form helium atoms as about 90%of the stars in the universe are main sequence Stars. The main sequence stars are less massive that they’re much cooler than stars like the sun.
Hence, we can conclude that the decreasing order or these stars are
White Dwarf stars > main sequence stars > giant stars > Supergiant stars

Note:
These four stars are very huge & massive & mostly are made up of hydrogen & helium. According to their diameter if they are arranged in an order then the white dwarf will have the smallest diameter while main sequence star is in the middle and then giant stars and then finally the Supergiant’s with largest diameter