Question

A sulphur containing species that cant be a reducing agent is

• A. $S{{O}_{2}}$
• B. $SO_{3}^{2-}$
• C. ${{H}_{2}}S{{O}_{4}}$
• D. ${{S}^{2-}}$

Answer 1

Answer: (C)

If the species is a reducing agent, it means it can be oxidised easily thus it should have oxidation number less than maximum values of oxidation number. In $S{{O}_{2}},SO_{4}^{2-}$ and ${{S}^{2-}},$ the oxidation number of S is $+\text{ }4,+\text{ }4,+\,6,$ and - 2 respectively. Therefore, $S{{O}_{2}},SO_{3}^{2-}$ and ${{S}^{2-}}$ can be reducing agent but $SO_{4}^{2-}$ cant be.