The _____ is a geologically brief period about 540 million years ago during which fossil evidence indicates Earth life became complex and diverse
A) Cambrian explosion
B) Paleozoic era
C) Renaissance
D) Ordovician
A
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What is the mass of a mole of oxygen gas?
a. 8.0 g b. 16 g c. 24 g d. 32 g
A wire of resistivity ? must be replaced in a circuit by a wire of the same material but four times as long. If, however, the total resistance is to remain as before, the diameter of the new wire must
A) be two times the original diameter. B) be the same as the original diameter. C) be one-fourth the original diameter. D) be one-half the original diameter. E) be four times the original diameter.
Young's Modulus: An aluminum wire and a steel wire, each of length 2.0 m, are hung from the ceiling. A 5.0-kg mass is suspended from the lower end of each wire. The aluminum wire has a diameter of 2.2 mm. What must be the diameter of the steel wire if it is to stretch the same distance as the aluminum wire, so that the two wires maintain equal lengths after the masses are attached? Young's modulus for aluminum is 0.70 × 1011 Pa and for steel it is 2.0 × 1011 Pa.
Fill in the blank(s) with the appropriate word(s).
What is the common trait of all main-sequence stars?
A) They are all spectral type G. B) They generate energy through hydrogen fusion in their core. C) They all have approximately the same mass. D) They are in the final stage of their lives.