Question

Caro’s acid is:
(A) ${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{5}}}$
(B) ${{\text{H}}_{\text{2}}}{{\text{S}}_2}{{\text{O}}_8}$
(C) ${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_3}$
(D) ${{\text{H}}_{\text{2}}}{{\text{S}}_2}{{\text{O}}_3}$

Answer 1

To answer this question, you must recall the names of the various oxo acids and peroxy acids of sulphur. Caro’s acid is named after its inventors and it is a peroxy acid formed by replacing a hydrogen atom in hydrogen peroxide by a sulfonyl hydroxide.

Complete step by step solution
Caro’s acid is the common name for peroxy mono sulphuric acid. It is also known as persulfuric acid and peroxy sulphuric acid. It is termed as peroxy mono sulphuric acid since there is only one sulfonyl hydroxide group. It was discovered by the scientist Heinrich Caro and thus is named after him.
The central atom of the acid is sulphur and the molecule is tetrahedral in shape. The systematic name for the compound is (dioxidanido) hydroxide- dioxide- sulphur. The sulphur atom is double bonded to two oxygen atoms, one hydroxyl group and a peroxy hydroxyl group.
The chemical formula for the compound is ${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{5}}}$ .
The correct answer is A..

Additional information:
The peroxy mono sulphuric acid is often confused with peroxydisulfuric acid. It has the chemical formula ${{\text{H}}_{\text{2}}}{{\text{S}}_2}{{\text{O}}_8}$ and is formed when both the oxygen atoms in hydrogen peroxide are replaced by two sulfonyl hydroxide groups. It is known as Marshall's acid. It was discovered by Professor Hugh Marshall and thus named after him as a mark of appreciation and respect towards him.

Note:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{5}}}$ is used as a disinfectant and has cleaning effects in a variety of applications. It is most commonly used for the treatment of water in swimming pools and denture cleaning.