Which of the following is correct of the longitudinal profile of most rivers?
A) It always changes at a constant rate from the headwater region to the sea.
B) It is convex in shape.
C) It is concave in shape.
D) It is gentle upstream and steep downstream.
C
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Corals are
A. cnidarians. B. fungi. C. plants. D. sponges.
Why does an atom with many valence electrons tend to gain electrons rather than lose any?
A) Atoms with many valence electrons tend to have relatively weak forces of attraction between the valence electrons and the nucleus. Therefore, the outer electrons are free to attract other electrons. B) There is stability in numbers. Atoms with many valence electrons are always attracting new electrons. C) The old adage that "he who has, gets" is also true in atomic structure. Atoms with many valence electrons can essentially overpower atoms with few valence electrons and attract additional electrons. D) Atoms with many valence electrons tend to have relatively strong forces of attraction between the valence electrons and the nucleus. This makes it easy for them to gain additional electrons.
Most of North America, including the United States and Canada, lies within the ________ zoogeographic realm
A) Australian B) Neotropical C) Palearctic D) Ethiopian E) Nearctic
A possible consequence of eutrophication is
A. sequestration of dissolved toxins in lake sediments. B. reduction of nutrient levels in a body of water. C. an increase in the biodiversity of the body of water. D. fish kills, because of the lowered dissolved oxygen in the water.