Assertion: pyridine | /r/MadeOf | a nitrogen atom
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Source sentences:
text: The pyridine of formula C5H5N is an aromatic heterocyclic compound containing a nitrogen atom; its main derivatives are 2-methylpyridine (or a-picoline), 3-methylpyridine (or (3-picoline) and 4-methylpyridine (or y-picoline), which have been known since the mid-19th century.