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4. d and f- block elements — Chemistry STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceChemistry4. d and f- block elements1 Mark
MCQ
Identify the incorrect statement.
  • ✓
    The oxidation states of chromium in $CrO _{4}\,^{2-}$ and $Cr _{2} O _{7}\,^{2-}$ are not the same
  • B
    $Cr ^{2+}\left( d ^{4}\right)$ is a stronger reducing agent than $Fe ^{2+}\left( d ^{6}\right)$ 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.
✓

Answer

Correct option: A.
The oxidation states of chromium in $CrO _{4}\,^{2-}$ and $Cr _{2} O _{7}\,^{2-}$ are not the same
a
Chromate $\left( CrO _{4}\,^{-2}\right) \Rightarrow$ oxidation state $=+6$

dichromate $\left( Cr _{2} O _{7}\,^{-2}\right) \Rightarrow$ oxidation state $=+6$

oxidation state are same.

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