Incorrect statement is

• $$\begin{gathered} \mathrm{stability} \mathrm{order}(\mathrm{Higher} \mathrm{Ox}.\mathrm{St}) :{\mathrm{Cr}}^{+3}<{{\mathrm{M}}_{\mathrm{o}}}^{+3}<{\mathrm{W}}^{+3} \\ \mathrm{Oxidising} \mathrm{power} \mathrm{order}: {\mathrm{Cr}}^{+3}>{\mathrm{M}}_{\mathrm{o}}^{+3}>{\mathrm{W}}^{+3} \end{gathered}$$

In transition elements from top to bottom higher oxidation state stability increases, hence oxidizing power decreases.

• Cr⁺² is a strong reducing agent, reduces H⁺ ions to hydrogen as it gets stable t2g³ configuration.  $\underset{{\mathrm{t}}_{2{\mathrm{g}}^4}}{2{\mathrm{Cr}}^{+2}}+2{\mathrm{H}}^{+}\to \underset{{\mathrm{t}}_{2{\mathrm{g}}^3}}{2\mathrm{C}}{\mathrm{r}}^{+3}+{\mathrm{H}}_2$
• Due to high hydration energy of Ni⁺² ion nickel SOP is very high, i.e., SRP is low (more negative)
• Simple halides of Mn with  +7 state were  not found but MnO₃F is known. So,4th statement incorrect.