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# The d-And-f-Block Elements

#### Multiple Choice Questions

1.

Which of the following is diamagnetic in nature ?

• [Fe(CN)6]3-

• ${\mathrm{NiCl}}_{4}^{2-}$

• [Ni(CO)4]

• [MnCl4]2-

C.

[Ni(CO)4]

Diamagnetic substances have all paired electron

(a) [Fe(CN)6]3- oxidation state of Fe = +3

It has one unpaired electron and is paramagnetic.

(b) [NiCl4]2-  Oxidation state of Ni= +2

It has two unpaired electrons and is paramagnetic.

(c) Ni(CO)4  Oxidation state of Ni=0

It has no unpaired electron and is diamagnetic.

(d) [MnCl4]2-  Oxidation state of Mn= + 2

1t is paramagnetic as it has five unpaired electrons.

2.

The actinoids exhibits more number of oxidation states in general than the lanthanoids. This is because

• the 5f orbitals are more buried than the 4f orbitals

• there is a similarity between 4f and 5f orbitals in their angular part of the wave function

• the actinoids are more reactive than the lanthanoids

• the 5f orbitals extend further from the nucleus than the 4f orbitals

D.

the 5f orbitals extend further from the nucleus than the 4f orbitals

The actinoids exhibit more number of oxidation states in general than the lanthanoids. This is because the 5f orbitals extend further from the nucleus than the 4f orbitals.

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3.

Cerium (Z = 58) is an important member of the lanthanoids. Which of the following statements about cerium is incorrect?

• The common oxidation states of cerium are +3 and +4

• Cerium (IV) acts as an oxidizing agent

• The +4 oxidation state of cerium is not known in solutions

• The +3 oxidation state of cerium is more stable than the +4 oxidation state

C.

The +4 oxidation state of cerium is not known in solutions

+3 and +4 states are shown by Ce in aqueous solution.

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4.

Which of the following factors may be regarded as the main cause of lanthanide contraction?

• Poor shielding of one of 4f electron by another in the subshell

• Effective shielding of one of 4f electrons by another in the subshell

• Poorer shielding of 5d electrons by 4f electrons

• Greater shielding of 5d electrons by 4f electrons

A.

Poor shielding of one of 4f electron by another in the subshell

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5.

The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate solution is

• +4

• +6

• +2

• +3

D.

+3

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6.

The lanthanide contraction is responsible for the fact that

• Zr and Nb have similar oxidation state

• Zr and Zn have the same oxidation

C.

Due to Lanthanide contraction.

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7.

The stability of dihalides of Si, Ge, Sn and Pb increases steadily in the sequence

• GeX2 << SiX2 << SnX2<< PbX2

• SiX2 << GeX2 << PbX2<< SnX2

• SiX2 << GeX2 << SnX2<< PbX2

• PbX2<< SnX2 << GeX2 << SiX2

C.

SiX2 << GeX2 << SnX2<< PbX2

Due to inert pair effect, the stability of +2 oxidation state increases as we move down this group.

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8.

Lanthanoid contraction is caused due to

• the appreciable shielding on outer electrons by 4f electrons from the nuclear charge

• the appreciable shielding on outer electrons by 5d electrons from the nuclear charge

• the same effective nuclear charge from Ce to Lu

• the imperfect shielding on outer electrons by 4f electrons from the nuclear charge

D.

the imperfect shielding on outer electrons by 4f electrons from the nuclear charge

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9.

A metal, M forms chlorides in it's +2 and +4 oxidation states. Which of the following statements about these chlorides is correct?

• MCl2 is more volatile than MCl4

• MCl2 is more soluble in anhydrous ethanol than MCl4

• MCl2 is more ionic than MCl4

• MCl2 is more easily hydrolysed than MCl4

C.

MCl2 is more ionic than MCl4

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10.

Identify the incorrect statement among the following –

• d-Block elements show irregular and erratic chemical properties among themselves

• La and Lu have partially filled d orbitals and no other partially filled orbitals

• The chemistry of various lanthanoids is very similar

• 4f and 5f orbitals are equally shielded

D.

4f and 5f orbitals are equally shielded

4f and 5f belong to different energy levels, hence the shielding effect is on them is not the same.Shielding of 4f is more than 5f

323 Views