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NCERT Solutions Class 11 Physics - Solved Exercise Question 2.23

Question 2.23:

The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 107 K, and its outer surface at a temperature of about 6000 K. At these high temperatures, no substance remains in a solid or liquid phase. In what range do you expect the mass density of the Sun to be, in the range of densities of solids and liquids or gases ? Check if your guess is correct from the following data : mass of the Sun = 2.0 × 1030 kg, radius of the Sun = 7.0 × 108 m.

Solution:

Mass of the Sun, M = 2.0 × 1030 kg
Radius of the Sun, R = 7.0 × 108 m
Volume of the Sun, V = (4/3) π R3
= (4/3) X (22/7) X (7 X 108)3
= (88/21) X 343 X 1024 = 1437.3 X 1024 m3
Density of the Sun = Mass / Volume = 2 X 1030 / 1437.3 X 1024 ~ 1.4 X 103 Kg / m3
The density of the Sun is in the density range of solids and liquids. This high density is attributed to the intense gravitational attraction of the inner layers on the outer layer of the Sun.