The key to identifying a black hole candidate in a binary system is that
A) one of the two stars cannot be seen.
B) the unseen companion in the system must have a sufficiently high mass.
C) the unseen star is a contact binary.
D) the system must be a very strong source of radio emissions.
E) the visible companion must be an evolving main sequence or giant star.
B
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A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, Which of the following is the balanced chemical reaction for this electrolysis reaction?
A. 2 NaCl (aq) + H2O ? 2 NaH (aq) + Cl2O (aq) B. 2 NaCl (aq) + 2 H2O ? 2 Na (s) + O2 (g) + 2 H2 (g) + Cl2 (g) C. 2 NaCl (aq) + H2O ? Na2O (aq) + 2 HCl (aq) D. 2 NaCl (aq) + 2 H2O ? 2 NaOH (aq) + Cl2 (g) + 2 H2 (g)
Since when we see Saturn's rings edge-on, they seem to disappear; they must be ________
Fill in the blank(s) with correct word
Single-Slit Diffraction: Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this?
A. Radio waves are unpolarized, whereas light is normally polarized. B. The wavelength of light is much smaller than the wavelength of radio waves. C. The wavelength of light is much greater than the wavelength of radio waves. D. Radio waves are coherent and light is usually not coherent. E. Radio waves are polarized, whereas light is usually unpolarized.
A student walks 1.0 mi west and then 1.0 mile north, after ward how far is she from her starting point?
A 1.0 mi B 1.4 mi C 1.6 mi D 2.0 Mi