Question 70

The Correct Answer is A **Why option A ("Alkylene oxides") is correct:** Ethylene oxide (also known as oxirane) is the simplest member of the chemical class known as alkylene oxides. An alkylene oxide is a cyclic ether that contains a three-membered ring with one oxygen atom and two carbon atoms, known as an epoxide ring. The "ethylene" part of the name refers to the two-carbon backbone (derived from ethylene/ethene), and the "oxide" part refers to the inclusion of the oxygen atom within the ring structure. Other common examples in this family include propylene oxide and butylene oxide. **Why the other options are incorrect:** * **B) Esters:** Esters are organic compounds derived from an acid (either organic or inorganic) in which at least one -OH (hydroxyl) group is replaced by an -O-alkyl (alkoxy) group. They contain the functional group R-COO-R'. Ethylene oxide does not contain this carbonyl structure ($\text{C=O}$). * **C) Alcohols:** Alcohols are organic compounds characterized by the presence of a hydroxyl functional group (-OH) bonded to a saturated carbon atom. Ethylene oxide is a cyclic ether and does not contain a hydroxyl group. * **D) Glycol ethers:** Glycol ethers are typically formed by the reaction of ethylene oxide (or other alkylene oxides) with an alcohol (like methanol or ethanol). They are linear or branched molecules containing both an ether linkage and a hydroxyl group (though the hydroxyl group may be further reacted). Ethylene oxide is a reactant used to *make* glycol ethers, but it is not a glycol ether itself; it is a cyclic ether (an epoxide).