Sessile benthos in a hypoxic zone generally begin to die when oxygen in the water drops to ________ ppm.
A. 5
B. 15
C. 0
D. 2
E. 10
Answer: D
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Whether a hydrogen-based energy system is environmentally cleaner than a fossil fuel system depends on ________
A) the source of energy used to produce the hydrogen B) the car driven C) governmental incentives for research D) the amount of fossil fuels that are invested in long-term storage E) the source of oxygen used for the process
On average, water in a river will have a longer residence time than water in the oceans.
Answer the following statement true (T) or false (F)
What is the youngest event represented in this block diagram?
A. retreat of the seas B. deposition of the top layer C. erosion of a canyon by a river D. formation of the lowest layer
The outermost edges of metropolitan areas are called suburbs
Indicate whether the statement is true or false