Which statement is true about Xylene as a solvent?

• A. Xylene is a universal solvent.
• B. Xylene is not a universal solvent.
• C. Xylene is a dehydration solvent.
• D. Xylene is used to stain tissues.

Answer: (B)

No solvent is universal; xylene is not. Universal solvents would dissolve a wide range of substances, including both polar and nonpolar materials, and water is often treated as the closest example of a universal solvent in biology—though even water has limits. Xylene is nonpolar and mixes well with nonpolar substances like paraffin, but it does not mix with water and cannot dissolve many polar compounds. In histology, xylene is used for clearing after dehydration, replacing alcohol and preparing the tissue for paraffin infiltration, not for dehydration itself and not for staining. Dehydration is done with graded alcohols, and staining uses dyes in aqueous or alcoholic solutions. So the statement that xylene is not a universal solvent correctly describes its role and properties.