An ion of a single pure element always has an oxidation number of . A. magnitude equal to its atomic number B. 1 C. None of these D. 0

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

the answer is d. 74.02