Problem

Problem

Choose correct statement(s) regarding the following reaction : Cr2O72−(aq.)+3SO32−(aq.)+8H+⟶2Cr3+(aq.)+3SO42−(aq.)+4H2O\text{Cr}_2\text{O}_7^{2-}(\text{aq.}) + 3\text{SO}_3^{2-}(\text{aq.}) + 8\text{H}^+ \longrightarrow 2\text{Cr}^{3+}(\text{aq.}) + 3\text{SO}_4^{2-}(\text{aq.}) + 4\text{H}_2\text{O} (a) Cr2O72−\text{Cr}_2\text{O}_7^{2-} is oxidising agent (b) SO32−\text{SO}_3^{2-} is reducing agent (c) The oxidation number of per S-atom in 3SO32−3\text{SO}_3^{2-} is increased by two (d) The oxidation number of per Cr-atom in Cr2O72−(aq.)\text{Cr}_2\text{O}_7^{2-}(\text{aq.}) is decreased by three
Intuitive explanation

This redox reaction hinges on tracking electron transfer between the dichromate ion (the oxidizing agent) and sulfite ion (the reducing agent). Identify which species gains electrons and which loses them by assigning oxidation states to chromium and sulfur before and after the reaction—this reveals the stoichiometry and confirms the equation is balanced. Understanding what gets oxidized versus reduced also tells you why dichromate works as a powerful oxidizer in acidic solution.

Intuitive explanation

This redox reaction hinges on tracking electron transfer between the dichromate ion (the oxidizing agent) and sulfite ion (the reducing agent). Identify which species gains electrons and which loses them by assigning oxidation states to chromium and sulfur before and after the reaction—this reveals the stoichiometry and confirms the equation is balanced. Understanding what gets oxidized versus reduced also tells you why dichromate works as a powerful oxidizer in acidic solution.

Browse the problem library