The level of decaying organic matter in water is indicated by what measure?
A) fecal coliform
B) eutrophication index
C) biochemical oxygen demand
D) nitrogen and phosphorus
C
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Glider A of mass of 1 kg and speed 1 m/s on a friction-free air track collides with a 5-kg glider B at rest. For an inelastic collision the combined-glider speed will be
A. 1/5 m/s. B. 1/4 m/s. C. 1/6 m/s. D. 1 m/s.
Why is water a necessary component of the melting process in subduction zones?
a) The addition of water lowers the friction experienced by rising magma. b) Water is a liquid, and rock needs to encounter a liquid in order to become a liquid. c) The addition of water lowers the melting temperature of rock. d) Water creates a buoyant force that allows the magma to rise. e) Water changes the density of the rock, allowing the rock to melt.
Sharing of electrons is possible in which type of chemical bond?
a. ionic b. metallic c. covalent d. nuclear
A decrease in the levels of ozone in the ozone layer:
a. may be related to the human use of chlorofluorocarbons b. is not a cause for concern to humans because the ozone layer is in the stratosphere c. cannot be attributed to any human activities d. has not been shown to be related to the incidence of skin cancers in humans