What is antimatter?
A) It consists of particles that are just like those of ordinary matter except with opposite properties, such as opposite charge.
B) It is matter that we infer to be in space by its gravitational influence, but that we have not yet identified.
C) It is a form of matter that has been hypothesized to exist but for which there is not yet any experimental evidence.
D) It is the material that makes up a complete antiuniverse that is identical to our own except that it is made from antimatter instead of matter.
A) It consists of particles that are just like those of ordinary matter except with opposite properties, such as opposite charge.
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Ancient philosophers and astronomers accepted without question-as first principles-that:
A) heavenly objects must move in circular paths at varying speeds. B) the planets are made of rock and gas, much like Earth. C) the Earth is motionless at the center of the Universe. D) there are many galaxies in the Universe.
A thin metal sheet in the xy plane carries current in the ?y direction. What is the direction of the magnetic field everywhere in the region above the sheet? 
in this case
A. points in the +x direction. B. points in the ?x direction. C. points in the +y direction. D. points in the ?y direction. E. points in the +z direction. F. points in the ?z direction. T. is zero.
What does the equivalent of an H-R diagram for galaxies, plotting luminosity versus color, show?
A) galaxies fill the diagram showing that there is no correlation between luminosity and color B) two clumps, one blue with relatively low luminosity, one red with relatively high luminosity, and a valley in between with few galaxies C) a continuum from faint, blue galaxies to bright, red galaxies D) a continuum from faint, red galaxies to bright, blue galaxies E) a main sequence, just as for stars
A mineral that looks glassy is said to have a(n) ______________ luster
Fill in the blank(s) with correct word