Based on the chemical formulas provided, the compound that can be classified as organic is C5H12O. Organic compounds are defined as molecules that contain carbon covalently bonded to other elements, most commonly hydrogen, oxygen, nitrogen, sulfur, phosphorus, and halogens (F, Cl, Br, I). The presence of C-H bonds is a key distinguishing feature of organic versus inorganic compounds.
C5H12O contains carbon atoms bonded to hydrogen and oxygen atoms in a covalent hydrocarbon structure, specifically an alkane with 5 carbon atoms and 12 hydrogen atoms. Alkanes are a fundamental class of organic compounds composed of single-bonded carbon chains with the general formula CnH2n+2.
The other chemical formulas provided represent inorganic compounds, which do not contain carbon-hydrogen bonds. While CO3 (carbonate) and CN (cyanide) contain carbon, the carbon is bonded to oxygen or nitrogen, not hydrogen.
KMnO4 is potassium permanganate, an ionic compound composed of K+ cations and MnO4- anions. Its carbonless composition and ionic structure classify it as inorganic.
MgCO3 is magnesium carbonate, containing the CO32- carbonate ion. Carbonate is classified as an inorganic polyatomic ion, even though it contains carbon.
NaNO3 is sodium nitrate, an ionic compound of Na+ cations and NO3- anions. It is composed of inorganic ions and contains no carbon.
Fe2O3 is iron(III) oxide, an ionic metal oxide compound. Its Fe3+ and O2- ions are inorganic.
In summary, the defining feature that distinguishes organic compounds is the presence of covalently bonded carbon-hydrogen structures. This is only seen in C5H12O out of the examples provided. The methods of structural determination, such as IR spectroscopy, X-ray diffraction, and NMR spectroscopy, allow reliable identification of the presence or absence of C-H bonds to differentiate organic from inorganic compounds.