Ans 8. (a) In the stage (F) on the H-R diagram of any medium mass star such as our sun, most probably forms a high density entity known as the red giant. This red giant, in their later stages, emit what is called “planetary nebula“.
Ans 8 . (b) Planetary nebula, is a type of emission consisting of an expanding and glistening shells of ionized gas ejected from the surface of the red giants, which is the fate of these red giants upon thier last stages.
Ans 9. (a) As the density increases further from the previous stages, Stage G is called the White dwarf stage of a star.
Ans 9 (b) The effective stellar size of this white dwarf is very often lesser than that, about half of the Sun itself, but the volumes of these stellar remanants are often reduced to that of the Earth, resulting in high to very high specific gravities or density.