Chemically, clean [non-polluted] air is
A) an element. B) a mixture. C) a compound. D) an isotope.
B
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The best places for life to have formed on Earth are believed to have been
a. near the south pole on the ice. b. on the continent of Africa in the areas with no water. c. in liquid water, probably in the oceans or pools of water.
Which of the following statements about the rings of the four jovian planets is not true?
A) All rings lie within their planet's Roche zone. B) All the particle orbits are fairly circular, near their planet's equatorial plane. C) All have gaps and ringlets, probably due to gap moons, shepherd moons, and orbital resonances. D) All probably look much like they did when the solar system first formed. E) All are made of individual particles of rock or ice that orbit in accord with Kepler's laws: inner ring particles orbiting faster, and outer ring particles orbiting slower.
All of the ________ now observed must be primordial
Fill in the blank(s) with correct word
Two point charges, separated by 1.5 cm, have charge values of +2.0 and -4.0 µC, respectively. Suppose we determine that 10 field lines radiate out from the +2.0-µC charge. If so, what might be inferred about the -4.0 mC charge with respect to field lines?
a. 40 radiate in c. 5 radiate out b. 20 radiate out d. 20 radiate in