Incorrect statement is

•  ${\mathrm{S}}_2{\mathrm{O}}_8^{-2}+2{\mathrm{I}}^{-}\to 2{\mathrm{SO}}_4^{-2}+{\mathrm{I}}_2$

Mechanism:

$$\begin{gathered} 2{\mathrm{Fe}}^{+3}+2{\mathrm{I}}^{-}\to 2{\mathrm{Fe}}^{+2}+{\mathrm{I}}_2 \\ 2{\mathrm{Fe}}^{+2}+{\mathrm{S}}_2{\mathrm{O}}_8^{-2}\to 2{\mathrm{Fe}}^{+3}+2{\mathrm{SO}}_4^{-2} \end{gathered}$$

In the above reaction moles of  Fe⁺³ ions before the reaction and after the reaction remains same, hence Fe⁺³ ion acts as catalyst.

Fe⁺² ion is formed as intermediate. (True)

• Interstitial compounds are chemically inert, hence they are using as refractory materials.(False).
• Difference between the atomic radii of alloy forming metals must be about 15% (True)
• ${\mathrm{V}}_2{\mathrm{O}}_3 \mathrm{and} {\mathrm{V}}_2{\mathrm{O}}_4$ are basic and ${\mathrm{V}}_2{\mathrm{O}}_5$is amphoteric oxide(True)