While we know of thousands of quasars, it is likely none of them still exist today. Explain
What will be an ideal response?
Quasars are associated with the gravitational collapse that gives birth to galaxies, and as they sweep up the accreting matter around them, soon their supply of fuel must become depleted, and they evolve into normal galactic nuclei; Seyfert galaxies are probably good examples of this change. No quasar has been observed closer than a billion light-years distant, so the last ones probably died out a billion years ago.
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Beyond the formation of iron, nuclear energy can be produced only by
A) fusion of still heavier elements. B) ionization of the radioactive nuclei. C) fission of heavy nuclei back toward lighter ones. D) gravity. E) the dark force.
A solution of what sugar is used for intravenous feeding in a hospital?
a. Sucrose b. Fructose c. Glucose d. Lactose
Charge in an Electric Field: A pair of charged conducting plates produces a uniform field of 12,000 N/C, directed to the right, between the plates. The separation of the plates is 40 mm. An electron is projected from plate A, directly toward plate B, with an initial speed of v0 = 2.0 × 107 m/s. What is the speed of the electron as it strikes plate B? (e = 1.6 × 10-19 C, melectron = 9.11 × 10-31 kg) 
A. 1.2 × 107 m/s B. 1.5 × 107 m/s C. 1.8 × 107 m/s D. 2.1 × 107 m/s E. 2.4 × 107 m/s
Studies of remanent magnetism in rocks spreading from the Mid-Atlantic Ridge reveal symmetric bands of magnetic anomalies. These anomalies provide
a. support for the idea of continental drift. b. evidence of Earth's magnetic pole reversals. c. both (A) and (B). d. neither (A) nor (B).