Mixtures of phenolics, aldehydes, and ketones are examples of which type of mixtures?

• A. Immiscible substances
• B. Hygroscopic substances
• C. Deliquescent substances
• D. Eutectic mixtures

Answer: (D)

A eutectic mixture is formed when different components interact so that the whole system melts at a single, much lower temperature than any of the pure substances. In mixtures of phenolics, aldehydes, and ketones, the abundant polar groups (like hydroxyls and carbonyls) engage in hydrogen bonding and strong dipole interactions. These interactions disrupt the individual crystal lattices and allow the components to pack together in a way that lowers the overall melting point. At the specific eutectic composition, the mixture transitions from solid to liquid at that lowered temperature, producing a sharp melting point unique to the mixture. The other options describe moisture-related properties or immiscibility, which don’t account for the lowered melting point seen in a eutectic system.