Stable cobalt atoms that have the same atomic number as the element cobalt, but differ in atomic weight. Co-59 is a stable cobalt isotope.
Isotopes, Cobalt
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Air
The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
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Water
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)