Spectra for the Cygnus loop and the Orion nebula are shown above. Which of these is seen in the Orion nebula, but is not clearly visible in the Cygnus loop spectrum?
A) ionized sulfur B) atomic helium C) atomic hydrogen D) ionized oxygen
B
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In the hypothetical atomic interaction shown in figure C9.13, the force between the atoms is attractive within what ranges of the interatomic separation r? 
A. For all r B. For r < 0.06 nm and r > 0.2 nm C. For 0.06 nm < r < 0.2 nm D. For 0.12 nm < r < 0.25 nm E. For r < 0.12 nm and r > 0.25 nm
As shown in the figure, a container has a vertical tube, whose inner radius is 32.00 mm, connected to it at its side. An unknown liquid reaches level A in the container and level B in the tube level A being 5.0 cm higher than level B. The liquid supports a 20.0 cm high column of oil, between levels B and C, whose density is 460 kg.m-3. What is the density of the unknown liquid?
A. 1800 kg/m3
B. 1600 kg/m3
C. 1400 kg/m3
D. 2000 kg/m3
E. 1700 kg/m3
If a person is farsighted the corrective lens will
a. take an object at the near point and form an image at 25 cm. b. take an object at 25 cm and form an image at the near point. c. take an object at infinity and form an image at 25 cm. d. take an object at infinity and form an image at the near point.
One common way to polarize a beam of light is to
A. slow it down using a piece of glass. B. filter out the longest wavelengths of the spectrum. C. use a sheet of Polaroid material. D. filter out the shortest wavelengths of the spectrum.