Question

Acidified solution of chromic acid on treatment with $H_2{O}_2$ gives blue colour which is due to -

• A. $Cr{O}_3+H_{2}O+O_2$
  
• B. $C{r}_2{O}_3+H_{2}O+O_2$
  
• C. $Cr{O}_5+H_{2}O$
  
• D. $H_{2}C{r}_2{O}_7+H_{2}O+O_2$

Answer 1

The correct option is C

$Cr{O}_5+H_{2}O$

$k_{2}C{r}_2{O}_7+H_{2}S{O}_4+4H_2{O}_2\to 2Cr{O}_5+k_{2}S{O}_4+5H_{2}O$
chromic peroxide
The blue colour due to chromic peroxide fades away gradually due to decomposition of $Cr{O}_5$ to $C{r}^{3+}$ ions and oxygen.