Question

Peroxy linkage is present in:
(A) Caro’s acid
(B) Pyrosulfuric acid
(C) Sulfurous acid
(D) Dithionic acid

Answer 1

If the compound has two oxygen atoms bonded by a single bond, then the compound has a peroxy linkage. The Peroxy linkage is represented as $-O-O-$.

Complete step by step solution:
If the compound has two oxygen atoms bonded by a single bond, then the compound has peroxy linkage. The Peroxy linkage is represented as $-O-O-$.
So, let us see the structures of all the options one by one:
(A)- Caro’s acid: Caro’s acid is also known as Peroxomonosulfuric acid. This is an oxoacid of the sulfur element. The formula of Caro's acid is ${{H}_{2}}S{{O}_{5}}$. The structure of Caro’s acid is given below:

This compound has one peroxy linkage.
(B)- Pyrosulfuric acid: Pyrosulfuric acid is also known as oleum. It is also an oxoacid of the sulfur element. The formula of Pyrosulfuric acid is ${{H}_{2}}{{S}_{2}}{{O}_{7}}$. The structure of Pyrosulfuric acid is given below:

This compound doesn’t have a peroxy linkage.
(C)- Sulfurous acid: Sulfurous acid is an element that has a lone pair on the sulfur element. It is also an oxoacid of the sulfur element. The formula of Sulfurous acid is ${{H}_{2}}S{{O}_{3}}$. The structure of Sulfurous acid is given below:

This compound doesn’t have a peroxy linkage.
(D)- Dithionic acid: Dithionic acid is an oxoacid of the sulfur element. The formula of Dithionic acid is ${{H}_{2}}{{S}_{2}}{{O}_{6}}$. The structure of Dithionic acid is given below:

This compound doesn’t have a peroxy linkage.

Therefore, the correct answer is an option (a)- Caro’s acid.

Note: Marshall’s acid or Peroxodisulfuric acid is also an oxoacid of the sulfur element. The formula of Marshall's acid is ${{H}_{2}}{{S}_{2}}{{O}_{8}}$. Other than Caro’s acid, Marshall’s acid is the compound of sulfur which has peroxy linkage. The structure is given below: