The incorrect statement among the following is :

$\mathrm{VOSO}_{4}$ is a reducing agent

Red colour of ruby is due to the presence of $\mathrm{CO}^{3+}$

$\mathrm{Cr}_{2} \mathrm{O}_{3}$ is an amphoteric oxide

$\mathrm{RuO}_{4}$ is an oxidizing agent