<span>Carbon dioxide is essential for photosynthesis.</span>
Photosynthetic organisms use the process of photosynthesis to produce their energy. During this process they also take in carbon dioxide and release oxygen. If there were less of such organisms, there would be more carbon dioxide and less oxygen in the atmosphere.
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Recall that a period is horizontal, and a group is vertical.
So if cobalt is moving "down" a period, it would be most logical to say that it would be Ni, or nickel. It could also be Copper, Zinc, Gallium, and so on. Make sense?
Answer:
Rocks can be divided into three basic classifications: igneous, sedimentary, and metamorphic. The following tests are used by experts to classify rocks: Hardness Test Minerals are scaled in range from 1 to 10, with 1 being softest and 10 hardest. The method of determining hardness is the scratch test.
