ANS:C - H₂S₂O₇

The chemical formula of oleum is H₂S₂O₇. The chemical formula of oleum is H₂S₂O₇, and here’s an explanation of its composition and significance:

Composition:

1. Sulfuric Acid Derivative:
   • Oleum is a solution of sulfur trioxide (SO₃) in sulfuric acid (H₂SO₄). It can be seen as a concentrated form of sulfuric acid containing extra sulfur trioxide.
2. Molecular Structure:
   • The formula H₂S₂O₇ indicates that oleum consists of two sulfur atoms, seven oxygen atoms, and two hydrogen atoms. This structure reflects its acidic nature and high sulfur content.

Properties:

1. Highly Corrosive:
   • Oleum is a strong acid and is highly corrosive, capable of reacting violently with water and organic materials.
2. Viscous Liquid:
   • It appears as a thick, oily liquid, which can vary in concentration depending on the amount of dissolved SO₃.

Production:

1. Manufacturing Process:
   • Oleum is typically produced during the contact process for sulfuric acid production, where sulfur dioxide is oxidized to sulfur trioxide, which is then absorbed in existing sulfuric acid.

Applications:

1. Industrial Use:
   • Oleum is used in the production of sulfuric acid, in chemical synthesis, and as a dehydrating agent in various chemical processes.
2. Sulfonation:
   • It is used in the sulfonation of organic compounds, important in the manufacturing of detergents, dyes, and pharmaceuticals.

Summary: