Astronomy quiz question: interstellar hydrogen hyperfine lines

Astronomy 210 Quiz 6, spring semester 2012
Cuesta College, San Luis Obispo, CA

Radio waves emitted from cold hydrogen gas clouds provides evidence of:
(A) spiral arms extending across the entire Milky Way disk.
(B) the central supermassive black hole.
(C) dark matter.
(D) unequal amounts of matter and antimatter.

Correct answer: (A)

Radio waves are relatively unaffected by interstellar gas and dust, and enable the locations of cold hydrogen gas clouds in most of the Milky Way to be mapped.

Section 30674
Exam code: quiz06niLl
(A) : 16 students
(B) : 5 students
(C) : 5 students
(D) : 4 students

"Success level": 53% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.44