Question

What is the primary visible color of an emission nebula? a. red due to ionized hydrogen atoms b. blue due to ionized helium atoms c. red because of reddening by dust d. black, because of dust e. blue from the scattering of light off the tiny molecules

Answer 1

Answer is A. Red due to ionized hydrogen atoms.

Step-by-step explanation:

Note that nebula color depends on its chemical composition and its degree of ionization. Because of the prevalence of hydrogen and relative low of ionization energy, its emission appears red.