d and f-Block Elements Test

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d and f-Block Elements Test - 7

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Weekly Quiz Competition

Question 1
1 / -0

The species with the largest and smallest radii among the 3d series are respectively

A
Sc and Co

B
Sc and Zn

C
Cr and Mn

D
Zn and Sc

Solution

In transition elements, the atomic radius first decreases on moving across the period due to increase in the effective nuclear charge, remains steady towards the middle as the increase in the effective nuclear charge is balanced by the increase in repulsive forces due pairing and further increases as the electronic repulsions dominate.

Sc – 144 pm
Co – 116 pm
Question 2
1 / -0

Which among the following species has a radius greater than that of Fe³⁺?

A
Co³⁺

B
Ni⁴⁺

C
Fe²⁺

D
None of the above

Solution

For the same element, the ion in the higher oxidation state has a smaller radius.
Question 3
1 / -0

Cu⁺ ion is not stable in aqueous solutions and it invariably exists as Cu²⁺ in them because

A
second ionisation energy of Cu is lower than the first

B
hydration energy of Cu¹⁺ is higher

C
hydration energy of Cu²⁺ is higher

D
second ionisation energy of Cu is higher

Solution

The high value of hydration for Cu²⁺ compensates for high ionisation energy.
Question 4
1 / -0

In which of the following species is manganese in the lowest oxidation state?

A
Mn₂O₇

B
MnO₄^-

C
MnO₄^2-

D
MnF₄

Solution

Transition elements show higher oxidation states in their oxides than in their fluorides as fluorine can form only single bonds, but oxygen can form double bonds.
Question 5
1 / -0

To which of the following categories will the given reaction belong?

2Cu⁺→Cu + Cu²⁺

A
Oxidation

B
Displacement

C
Reduction

D
Disproportionation

Solution

Copper is getting oxidised as well as reduced.
Question 6
1 / -0

Which of the following pairs of elements exhibits the stable configuration of half-filled 4f-orbitals?

A
Yb and Lu

B
Eu and Gd

C
La and Eu

D
Gd and Yb

Solution

Eu: [Xe] 4f⁷ 5d⁰ 6s²
Gd: [Xe] 4f⁷ 5d¹ 6s²
Question 7
1 / -0

Which of the following statements is incorrect?

A
Successive shrinkages in the atomic size are referred to as lanthanoid contractions.

B
Actinoids are more reactive than lanthanoids.

C
Salts of La³⁺ and Lu³⁺ are colourless.

D
Eu²⁺ and Yb²⁺ are good oxidising agents.

Solution

Eu²⁺ and Yb²⁺ are good reducing agents because of their tendencies to get oxidised to their more common oxidation state (+3).
Question 8
1 / -0

Compounds of most lanthanoids occur in +3 oxidation state. Which of the following formulae of the compounds of lanthanoids is incorrect?

A
Sulphides, Ln₂S₃

B
Oxides, Ln₂O₃

C
Nitrides, LnN₃

D
Hydroxides, Ln(OH)₃

Solution

The correct formula is LnN.
Question 9
1 / -0

Which of the following pairs represents good reducing and oxidising agents, respectively?

A
La³⁺ and Eu²⁺

B
Tb⁴⁺ and Eu²⁺

C
Yb³⁺ and Eu²⁺

D
Yb²⁺ and Eu²⁺

Solution

Tb⁴⁺ has a stable configuration of half-filled 4f orbitals, but can get reduced to its more common +3 oxidation state. Eu²⁺ has a stable configuration of half-filled 4f orbitals, but can get oxidised to its more stable +3 oxidation state.
Question 10
1 / -0

Which of the following statements is incorrect?

A
Besides the common +3 oxidation state, actinoids can exhibit +4, +5, +6 and +7 oxidation states.

B
Actinoids are less basic than lanthanoids.

C
Actinoids are radioactive.

D
Actinoids have a greater tendency for complex formation.

Solution

Lanthanoids are less basic than actinoids because they have a greater percentage of covalent character.

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d and f-Block Elements Test - 7

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d and f-Block Elements Test - 7

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Question 1

Sc and Co

Sc and Zn

Cr and Mn

Zn and Sc

Solution

Question 2

Co3+

Ni4+

Fe2+

None of the above

Solution

Question 3

second ionisation energy of Cu is lower than the first

hydration energy of Cu1+ is higher

hydration energy of Cu2+ is higher

second ionisation energy of Cu is higher

Solution

Question 4

Mn2O7

MnO4-

MnO42-

MnF4

Solution

Question 5

Oxidation

Displacement

Reduction

Disproportionation

Solution

Question 6

Yb and Lu

Eu and Gd

La and Eu

Gd and Yb

Solution

Question 7

Successive shrinkages in the atomic size are referred to as lanthanoid contractions.

Actinoids are more reactive than lanthanoids.

Salts of La3+ and Lu3+ are colourless.

Eu2+ and Yb2+ are good oxidising agents.

Solution

Question 8

Sulphides, Ln2S3

Oxides, Ln2O3

Nitrides, LnN3

Hydroxides, Ln(OH)3

Solution

Question 9

La3+ and Eu2+

Tb4+ and Eu2+

Yb3+ and Eu2+

Yb2+ and Eu2+

Solution

Question 10

Besides the common +3 oxidation state, actinoids can exhibit +4, +5, +6 and +7 oxidation states.

Actinoids are less basic than lanthanoids.

Actinoids are radioactive.

Actinoids have a greater tendency for complex formation.

Solution

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Co³⁺

Ni⁴⁺

Fe²⁺

hydration energy of Cu¹⁺ is higher

hydration energy of Cu²⁺ is higher

Mn₂O₇

MnO₄^-

MnO₄^2-

MnF₄

Salts of La³⁺ and Lu³⁺ are colourless.

Eu²⁺ and Yb²⁺ are good oxidising agents.

Sulphides, Ln₂S₃

Oxides, Ln₂O₃

Nitrides, LnN₃

Hydroxides, Ln(OH)₃

La³⁺ and Eu²⁺

Tb⁴⁺ and Eu²⁺

Yb³⁺ and Eu²⁺

Yb²⁺ and Eu²⁺