(i) $In{\mathrm{VOSO}}_4,{}^{\text{'}}\mathrm{V}^{\text{'}}$ is in $+4$ oxidation state.
So it act as oxidising agent.
(ii) ${\mathrm{Cr}}_2{\mathrm{O}}_3$ is an amphoteric oxide.
(iii) $In{\mathrm{RuO}}_4,$ $\text{'}\mathrm{Ru}\text{'}$ is in $+8$ oxidation state. So it act as oxidising agent.
(iv) Red colour of ruby is due to the presence of ${\mathrm{Cr}}^{+3}$ ions in ${\mathrm{Al}}_2{\mathrm{O}}_2.$