Question

The color of a star is determined by its temperature; the hottest stars are _______________ and the coolest stars are _____________________ in color.
A) Blue and white
B) White and red
C) Blue and red
D) Blue and yellow

Answer 1

Hint
Stars produce light through nuclear reactions inside it by using energy stored in their nucleus at the center of atoms. Reactions inside stars make the star extreme hot and glow in different lights according to their temperature.

Complete step by step solution
Stars emit electromagnetic radiations at all wavelengths because some atoms and molecules move or vibrate at denser gas so in collisions some atoms or molecules move slower than average and some atoms or molecules move faster than average. So when we look at the stars emitting electromagnetic radiations, we find the spectrum of wavelengths and energies.
Now, the object at higher temperature emits more power at wavelengths than the object at lower temperature. That means a hotter star emits more power at wavelengths than a cooler star.
Remember that higher the temperature, wavelength will be shorter at which the maximum power emitted. Also shorter wavelength means higher frequency and energy. It means a hotter star gives more energy at short wavelengths than a cold star.
Since blue color has shorter wavelength so it is a sign of hotter star and red color has longer wavelength so it is the sign of cold star.
Therefore, the hottest stars are blue in color and the coolest stars are red in color.
Hence, the correct answer is option (C).

Note
Learn about electromagnetic radiations and their wavelength. Also learn about the all colors and their wavelength. Learn about wien’s law to determine the temperature of stars numerically.