Stars are heavenly bodies made up of hot burning gases. Which of the following statements are TRUE?
(A) A star's color indicates the temperature of its surface.
(B) Blue color denotes the minimum temperature.
(C) A neutron star is about 20 km in diameter and has a mass of about 1.4 times that of the Sun.
(D) Neutron stars are formed by supernova explosions.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (C) and (D) only
A star shines because of nuclear fusion in its core. Its colour depends on its surface temperature, and a very heavy star ends its life in a supernova that can leave behind a neutron star.
(A) A star’s color indicates the temperature of its surface. Correct. A hotter body gives out more of its light at shorter wavelengths, so the colour of a star tells its surface temperature.
(B) Blue color denotes the minimum temperature. Incorrect. Blue stars are the hottest, above about 10,000 °C; red stars are the coolest, about 3,000 °C, and yellow stars like the Sun lie in between.
(C) A neutron star is about 20 km in diameter and has a mass of about 1.4 times that of the Sun. Correct. A neutron star packs a mass of about 1.4 solar masses into a ball only about 20 km across, which makes it one of the densest objects known.
(D) Neutron stars are formed by supernova explosions. Correct. When a massive star runs out of fuel, its core collapses and the outer layers are blown off in a supernova; the collapsed core that remains is a neutron star.