Correct Answer: Sodium hydroxide
Subject: 2025
Explanation: <p><strong>Key Fact:</strong> Saponification is the alkaline hydrolysis of fats and vegetable oils (fatty acid triglycerides) using a strong alkali, predominantly Sodium hydroxide ($NaOH$) to make hard soaps or Potassium hydroxide ($KOH$) for liquid/soft soaps.</p><p><strong>Additional Info:</strong> In this reaction, triglycerides react with $NaOH$ to yield soap (sodium salts of long-chain fatty acids like sodium stearate) and glycerol ($C_3H_8O_3$) as a valuable byproduct: $$\text{Fat/Oil} + 3NaOH \rightarrow \text{Glycerol} + 3\text{Soap}$$</p><p><strong>Why the other options are wrong:</strong> Acetic acid is an acid, not an alkali; Ethanol is a solvent; Esters are the reactants contained in fats, but the question asks which alkali compound is required to carry out the hydrolysis.</p><p><strong>Exam Trick:</strong> Soap = Sodium/Potassium salt of fatty acids $ ightarrow$ Requires $NaOH$ or $KOH$.</p><p><strong>Final Answer:</strong> Sodium hydroxide</p>