Question

Which of the following statements is/are correct about the reaction?
$4Cr{O}_5+6H_{2}S{O}_4\to 2C{r}_2(S{O}_4{)}_3+6H_{2}O+7O_2$

• A. It is disproportionation reaction
• B. It is an intramolecular redox reaction
• C. $Cr$ acts as an oxidant, whereas $O$ acts as a reductant
• D. $Cr{O}_5$ acts as oxidant and reductant both

Answer 1

Answer: (B), (C), (D)

The correct options are
B It is an intramolecular redox reaction
C $Cr{O}_5$ acts as oxidant and reductant both
D $Cr$ acts as an oxidant, whereas $O$ acts as a reductant

Oxidation state of $Cr$ in $Cr{O}_5=+6$.
It changes to $+3$ in $C{r}_2(S{O}_4{)}_3$.
$3e^{-}+C{r}^{6+}\to C{r}^{3+}$(reduction)
Whereas $O$ in $Cr{O}_5$ changes to $O_2$.
$2O^{⊝}\to O_2+2e^{-}$(oxidation)
So,
$Cr{O}_5$ acts as oxidant and reductant both, and also it is intramolecular redox reaction, since, in $Cr{O}_5$, both $Cr$ and $O$ undergoes oxidation and reduction reaction.
Hence, options A, B, C & D are correct.