Identify the incorrect statement.

• A
  The oxidation states of chromium in $CrO_{4}^{2-}$ and $Cr_{2}O_{7}^{2-}$ are not the same.
• B
  $Cr^{2+}(d^{4})$ is a stronger reducing agent than $Fe^{2+}(d^{6})$ in water.
• C
  The transition metals and their compounds are known for their catalytic activity due to their ability to adopt multiple oxidation states and to form complexes.
• D
  Interstitial compounds are those that are formed when small atoms like $H, C$ or $N$ are trapped inside the crystal lattices of metals.