Identify correct statements from below: A. The chromate ion is square planar. B. Dichromates are generally prepared from chromates. C. The green manganate ion is diamagnetic. D. Dark green coloured \(\mathrm{K}_{2} \mathrm{MnO}_{4}\) disproportionates in a neutral or acidic medium to give permanganate. E. With increasing oxidation number of transition metal, ionic character of the oxides decreases. Choose the correct answer from the options given below:

d and f Block Elements — JEE Main · 2024 · 31 Jan 2024 · Shift 1 Question with Solution

Identify correct statements from below:
A. The chromate ion is square planar.
B. Dichromates are generally prepared from chromates.
C. The green manganate ion is diamagnetic.
D. Dark green coloured

K_{2} MnO_{4}

disproportionates in a neutral or acidic medium to give permanganate.
E. With increasing oxidation number of transition metal, ionic character of the oxides decreases.

Choose the correct answer from the options given below:

(A)B, C, D only
(B)A, D, E only
(C)A, B, C only
(D)B, D, E only✓ Correct

Answer: (D)

Solution

A. The chromate ion,

Cr O_{4}^{2 -}

, is tetrahedral, not square planar -- false.

B. Dichromates are indeed prepared from chromates by acidification:

2 Cr O_{4}^{2 -} + 2 H^{+} \to C r_{2} O_{7}^{2 -} + H_{2} O

-- true.

C. The green manganate ion,

Mn O_{4}^{2 -}

, has one unpaired electron and is paramagnetic, not diamagnetic -- false.

D. Dark green

K_{2} Mn O_{4}

disproportionates in neutral or acidic medium to give permanganate (and

Mn O_{2}

) -- true.

E. Ionic character of transition metal oxides decreases as the oxidation state of the metal increases (higher charge density polarises the oxide ion more, increasing covalent character) -- true.

So the correct statements are B, D and E only.

JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Single correct option

JEE Main · 2024 · 31 Jan 2024 · Shift 1 · d and f Block Elements

Solution

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