Question

Functional group present in sulphonic acid is :

• A. SO₄H
• B. SO₃H
• C.

  

• D. -SO₂

Answer 1

The Correct Option is B

The inquiry concerns the functional group within sulphonic acids. An examination of the provided options follows:

1. Option SO₄H: The notation SO₄H is not a recognized standard for any functional group in organic chemistry and does not represent the sulphonic acid group.
2. Option SO₃H: This is the accurate designation for the sulphonic acid functional group, represented as -SO₃H. It comprises a sulfur atom bonded to three oxygen atoms and one hydrogen atom. Its structure is depicted as: \(\text{-}SO_3H\).
3. Option -SO₂: This denotes the sulfone group, characterized by a sulfur atom with double bonds to two oxygen atoms, distinct from the sulphonic acid group.
4. Option with image: Assuming the image presents an alternative incorrect representation of the sulphonic acid functional group, its specific identification is secondary to the correct formula.

Therefore, the correct functional group for sulphonic acids is \(\text{-}SO_3H\), aligning with option SO₃H. This group is definitive of sulphonic acids, where the sulfur atom achieves a complete octet via its bonds with oxygen and hydrogen atoms.