Please help with the following. True or False 1. The interstellar medium is comp
ID: 2304177 • Letter: P
Question
Please help with the following.
True or False 1. The interstellar medium is composed mostly of gaseous atoms of hydrogen. T An H II region is composed mostly of neutral atoms of gaseous hydrogen. F 3. 2. The great Nebula in Orion emits a bright line spectrum. F 4. A star with a spectral classification of F7 emits the ultraviolet photons needed to ionize hydrogen. T 5. Dust absorbs the visible light emitted by stars and re-emits it as infrared light. T 6. The existence of forbidden spectral lines from emission nebulae indicates that the region has a low density. F 7. Reflection nebulae emit a dark line spectrum. T 8. Bok globules are examples of dark nebulae. T 9. Interstellar extinction causes stars to appear closer than they really are. F 10. Interstellar reddening makes stars appear hotter than they really are. T 11. The spectrum of a star with a B8 spectral classification shows strong ionized calcium lines. The spectral lines originate from the interstellar medium. T 12. The spectral lines that originate from the interstellar medium are wide spectral lines. F 13. If there are multiples of a single spectral line, this indicates that the light may have traveled through several clouds in the interstellar medium. F 14. Radio waves with a wavelength of 21 cm are used to detect H I clouds. T 15. When molecules rotate and vibrate they emit far-infrared and radio waves. T 16. The detection of carbon monoxide is used to detect giant molecular clouds. T 17. Molecules cool a cloud and are usually located on the edges of the cloud. T 18. The model of the ISM presented in this chapter consists of H I clouds, giant molecular clouds, the intercloud medium and hot coronal gas. F 19. In the gas-star-gas cycle all matter is recycled and not lost to space. F 20. Small particles tend to scatter blue light. TExplanation / Answer
Answer:
(1) the interstellar medium is composed mostly of gaseous atoms of hydrogen, this is True. Approximately 99% of the interstellar medium is composed of interstellar gas, and of its mass, about 75% is in the form of hydrogen (either molecular or atomic), with the remaining 25% as helium.
(2) An H II region is composed mostly of neutral atoms of gaseous hydrogen, this is false. H II region consisting of ionized hydrogen atoms.
(3) The great nebula in orion emits a bright line spectrum, this is True.
(4) A star with a spectral classification of F7 emits the ultraviolet photons needed to ionize hydrogen, this is False.
(5) Dust absorbs the visible light emitted by stars and re-emit it as infrared light, this is True.
(6) The existence of forbidden spectral lines from emission nebulae indicates that the region has a low density. This is True.
(7) Reflection nebulae emit a dark line spectrum, this is True.
(8) Bok globules are examples of dark nebulae, this is also True.
(9) Interstellar extinction causes stars to appear closer than they really are. this is false.
(10) Interstellar reddening makes stars appear hotter than they really are, this is false.