We analyze each statement based on the NCERT text:

1. Catalytic Activity: Transition metals are known for catalytic activity due to their ability to adopt multiple oxidation states and form complexes . This statement is correct.
2. Interstitial Compounds: These are formed when small atoms like H, C, or N are trapped inside the crystal lattices of metals . This statement is correct.
3. Oxidation States: In chromate ($CrO_4^{2-}$): $x + 4(-2) = -2 \Rightarrow x = +6$. In dichromate ($Cr_2O_7^{2-}$): $2x + 7(-2) = -2 \Rightarrow 2x = 12 \Rightarrow x = +6$. The oxidation state of chromium in both ions is the same (+6) . Therefore, the statement claiming they are not the same is incorrect.
4. Reducing Agent: $Cr^{2+}$ is a stronger reducing agent than $Fe^{2+}$. $Cr^{2+}$ ($d^4$) changes to $Cr^{3+}$ ($d^3$), which has a stable half-filled $t_{2g}$ configuration. The standard electrode potential $E^{\ominus}(Cr^{3+}/Cr^{2+})$ is $-0.41 \text{ V}$, while $E^{\ominus}(Fe^{3+}/Fe^{2+})$ is $+0.77 \text{ V}$ . This statement is correct.