d and f Block Elements — JEE Main · 2009 · 12 Apr 2009 · Offline Question with Solution

In context with the transition elements, which of the following statements is incorrect ?
(1) In addition to the normal oxidation states, the zero oxidation state is also shown by these elements in complexes.
(2) In the highest oxidation states, the transition metal show basic character and form cationic complexes.
(3) In the highest oxidation states of the first five transition elements ( Sc to Mn ), all the 4 s and 3 d electrons are used for bonding.
(4) Once the

d^{5}

configuration is exceeded, the tendency to involve all the 3d electrons in bonding decreases.

(A)In addition to the normal oxidation states, the zero oxidation state is also shown by these elements in complexes.
(B)In the highest oxidation states, the transition metal show basic character and form cationic complexes.✓ Correct
(C)In the highest oxidation states of the first five transition elements ( Sc to Mn ), all the 4 s and 3 d electrons are used for bonding.
(D)Once the $d^{5}$ configuration is exceeded, the tendency to involve all the 3d electrons in bonding decreases.

Answer: (B)

Solution

In their highest oxidation states the transition metals are not basic but acidic, and instead of cationic species they form anionic oxo-complexes such as

Mn O_{4}^{-}

and

Cr O_{4}^{2 -}

. The statement claiming basic character and cationic complexes in the highest oxidation states is therefore the incorrect one, while the remarks about zero oxidation states in complexes, the full use of

4 s

and

3 d

electrons up to manganese, and the reluctance to involve all

3 d

electrons beyond

d^{5}

are all correct.

JEE Main · 2009 · 12 Apr 2009 · Offline · Single correct option

JEE Main · 2009 · 12 Apr 2009 · Offline · d and f Block Elements

Solution

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