How long did it take before free oxygen could build up in the atmosphere?

A. 2 billion years
B. 20 million years
C. 200 million years


Answer: A

Environmental & Atmospheric Sciences

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The harvest of organisms is more likely to be sustainable if organisms are captured

A) before they have had a chance to reproduce. B) while they are still in the egg or seed stages. C) after they have had a chance to reproduce. D) during the first year of their life.

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What is the ratio of parent atoms to daughter atoms after three half-lives?

What will be an ideal response?

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Some observers of the Middle East believe political tension over this resource could escalate to war in the next few years

A) brine B) cobalt C) high-grade coal deposits D) rare earth metals E) water

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What is the difference between a fracture zone and transform fault?

a) A transform fault is perpendicular to the mid-ocean ridge, but a fracture zone is not b) A transform fault is a crack in the crust, but a fracture zone is a hole in the crust that extends into the mantle c) A transform fault runs along a zone of weakness in the crust while a fracture zone runs along a zone of strong, erosion-resistant rock d) Transform faults run between offsets in a mid-ocean ridge while fracture zones extend beyond the offsets e) Transform faults are stationary while fracture zones have strike-slip motion

Environmental & Atmospheric Sciences