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:

(A), (C) and (D) only

The correct answer is Option (2) → (A), (C) and (D) only

(A) A star's color indicates the temperature of its surface. True. This is a fundamental concept in astronomy. According to Wien's Displacement Law, the peak wavelength of light emitted by a star is inversely proportional to its temperature.

(B) Blue color denotes the minimum temperature. False. In the stellar classification system, blue stars are the hottest (with surface temperatures often exceeding 30,000 K), while red stars are the coolest (around 3,000 K). Minimum temperature is denoted by red.

(C) A neutron star is about 20 km in diameter and has a mass of about 1.4 times that of the Sun. True. Neutron stars are incredibly dense. While they contain about 1.4 solar masses (known as the Chandrasekhar limit context), they are compressed into a sphere roughly the size of a city (about 20 km in diameter).

(D) Neutron stars are formed by supernova explosions. True. When a massive star (much larger than our Sun) runs out of fuel, its core collapses and the outer layers are blown away in a Type II Supernova. The remaining collapsed core becomes either a neutron star or a black hole.