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

• +4

• +6

• +2

• +2

Larger number of oxidation states are exhibited by the actinoids than those by the lanthanoids, the main reason being

• 4f orbitals more diffused than the 5f orbitals

• lesser energy difference between 5f and 6d than between 4f and 5d orbitals

• more energy difference between 5f and 6d than between 4f and 5d orbitals

• more energy difference between 5f and 6d than between 4f and 5d orbitals

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

• The chemistry of various lanthanoids is very similar

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 actinoids are more reactive than the lanthanoids

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

• SiX₂ << GeX₂ << SnX₂<< PbX₂

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 ionic than MCl₄

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 same effective nuclear charge from Ce to Lu

The lanthanide contraction is responsible for the fact that

• Zr and Y have about the same radius

• Zr and Nb have similar oxidation state

• Zr and Hf have about the same radius

• Zr and Hf have about the same radius

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

• Poorer shielding of 5d electrons by 4f electrons

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 +4 oxidation state of cerium is not known in solutions