When ethylene glycol is heated with acidified potassium permanganate, the main organic compound obtained is: (a) Acetaldehyde (b) Glyoxal (c) Formic acid (d) Oxalic acid

Potassium permanganate (KMnO4) is a powerful and widely used oxidizing agent in organic chemistry. Its ability to oxidize a range of organic molecules is leveraged in many chemical reactions. When dissolved in water, KMnO4 imparts a deep purple color due to the presence of the permanganate ion (MnO₄⁻).

In an acidic environment, potassium permanganate becomes particularly potent as it converts to manganese dioxide (MnO₂) and releases oxygen (O₂), which facilitates the oxidation of various compounds. Oxidation reactions involving KMnO4 can change the functional groups present in an organic molecule, as seen with the oxidation of ethylene glycol to a di-carboxylic acid. Chemists value KMnO4 for its specificity and the clarity of its color change upon completion of the reaction, which serves as a visual indicator.

Carboxylic acids are organic compounds characterized by the presence of a carboxyl group, which includes a carbonyl (C=O) and a hydroxyl (OH) group attached to the same carbon atom. The general formula can be written as R-COOH, where R represents the rest of the molecule. One of the most straightforward examples is formic acid (HCOOH), where R is a hydrogen atom.

Carboxylic acids are ubiquitous in nature and industry, involved in the creation of fragrances, plastics, pharmaceuticals, and as intermediates in biochemical pathways. The acidity of carboxylic acids stems from the potential for the hydroxyl hydrogen to dissociate, forming a carboxylate anion (RCOO⁻). In educating students for competitive exams like NEET, understanding the properties and reactions of carboxylic acids is essential, particularly because it can determine a molecule's reactivity and interaction with other compounds.

Organic chemistry is a significant section of the National Eligibility cum Entrance Test (NEET), a competitive exam for students aspiring to pursue medical studies in India. This subject tests the knowledge of carbon-containing compounds and their transformations. Analysis of organic reactions, identification of products, and understanding the underlying mechanisms are key components.

Candidates are often challenged with reactions that involve oxidizing agents like potassium permanganate, and the conversion of functional groups, a foundational concept being the oxidation of alcohols to carboxylic acids. Ethylene glycol's oxidation to oxalic acid represents a classic example of such conversions. Preparing for NEET requires a strong grasp of organic chemistry concepts, mechanistic pathways, and the application of these ideas to problem-solving, alongside being able to handle the empirical and molecular formulas of organic compounds.