Question

Which of the following can be oxidised by $SO_2$ ?

• A. $K_2Cr_2O_7$
• B. $Mg$
• C. $H_2O$
• D. All of these

Answer 1

Answer: (B)

$Mg$

Answer 2

With KCrO, SO works as reducing agent. ${K2Cr2O7 + H2SO4 + 3SO2 -> K2SO4 + Cr2(SO4)3 + H2O}$ With water the reaction is not a redox reaction, ${SO2 + H2O -> H2SO3}$ ${2Mg + SO2 -> 2MgO + S}$ ${3Mg + SO2 -> 2MgO + MgS}$