The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 47

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Weekly Quiz Competition

Question 1
1 / -0

The electronic configuration of actinoids can not be assigned with degree of certanity because of :

A
overlapping of inner orbitals

B
free movement of electron over all the orbitals

C
small energy difference between $$5f$$ and $$6d$$ levels

D
none of above

Solution

Since, there is a very small difference between the energies of 5f and 6d levels, thus the electron can go to 6d level or can remain in 5f level. Hence, the electronic configuration of actinides cannot be assigned with degree of certainty. Due to this, Ac and Th do not contain any 5f electron and Pu, Am and Bk No do not contain 6d electron.
Hence, option C is correct.
Question 2
1 / -0

Lanthanoid contraction implies :

A
Decrease in density

B
Decreases in mass

C
Decrease in ionic radii

D
Decrease in radioactivity

Solution

Lanthanoid contraction effect results from poor shielding of nuclear charge (nuclear attractive force on electrons) by 4f electrons; the 6s electrons are drawn towards the nucleus, thus resulting in a smaller atomic radius.
Hence, option C is correct.
Question 3
1 / -0

Most of the man-made synthetic elements occur:

A
in actinide series

B
in lanthanide series

C
in coinage metals

D
in alkaline earth metals

Solution

The first actinides to be discovered were Uranium by Klaproth in 1789 and Thorium by Berezelius in 1829, but most of the Actinides were $$man-made$$ products of the 20th century. Actinium and Protactinium are found in small portions in nature, as decay products of 253-Uranium and 238-Uranium.
Hence (A) is the answer.
Question 4
1 / -0

Arrange $$ Ce^{3+} , La^{3+} ,Pm^{3+}$$ and $$Yb^{3+} $$ in increasing order of their ionic radii:

A
$$ Yb^{3+} < Pm^{3+} < Ce^{3+} < La^{3+} $$

B
$$ Yb^{3+} < Pm^{3+} < La^{3+} < Ce^{3+} $$

C
$$ La^{3+} < Ce^{3+} < Yb^{3+} < Pm^{3+} $$

D
$$ Pm^{3+} < La^{3+} < Ce^{3+} < Yb^{3+}$$

Solution

It is observed that in the lanthanide series, there is a progressive decrease in the atomic and ionic radii with an increasing atomic number. This regular decrease with increase in atomic number is called lanthanide contraction. This is due to the weak shielding of f orbitals. This is observed even in the case of ions.
Question 5
1 / -0

The correct statement about the magnetic properties of $$[Fe(CN)_6]^{3-}$$ and $$[FeF_6]^{3-}$$ is: $$(Z=26)$$.

A
$$[Fe(CN)_6]^{3-}$$ is paramagnetic, $$[FeF_6]^{3-}$$ is diamagnetic

B
Both are diamagnetic

C
$$[Fe(CN)_6]^{3-}$$ is diamagnetic, $$[FeF_6]^{3-}$$ is paramagnetic

D
Both are paramagnetic

Solution
Question 6
1 / -0

Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour?

A
$$[Co(CN)_6]^{3-}$$

B
$$[Fe(CN)_6]^{3-}$$

C
$$[Mn(CN)_6]^{3-}$$

D
$$[Cr(CN)_6]^{3-}$$

Solution
Question 7
1 / -0

The radius of $$ La^{3+} $$ (atomic number of $$La = 57$$) is $$ 1.06 \mathring{A} $$ which one of the following given values will be closest to the radius of $$ Lu^{3+} $$ (atomic number of $$Lu = 71$$)?

A
$$ 1.40 \mathring{A}$$

B
$$ 1.06 \mathring{A}$$

C
$$ 0.85 \mathring{A} $$

D
$$ 1.60 \mathring{A} $$

Solution

In lanthanides, there is fairly regular decrease in the size with increasing atomic numbers. So, possible radius for $$Lu^{3+}$$ is $$0.85\ \overset{o}A.$$
Question 8
1 / -0

Ammonia solution dissolves fairly:

A
$$Hg_2Cl_2$$

B
$$PbCl_2$$

C
$$AgI$$

D
$$Cu(OH)_2$$

Solution

Ammonia solution dissolves fairly in $$Cu(OH)_2.$$ Copper(II) hydroxide reacts with a solution of ammonia to form a deep blue solution of tetramminecopper $$[Cu(NH_3)_4]^{2+}$$ complex ion.

$$Reaction:$$

$$Cu^{2+}+NH_3 \rightarrow [Cu(NH_3)_4]^{2+}$$

Option D is correct.
Question 9
1 / -0

Among $$d-$$block elements, the most abundant element belongs to :

A
first transition series

B
second transition series

C
third transition series

D
fourth transition series

Solution

Most abundantly found transition elements are iron and titanium.

Iron is the most abundant element, by mass, in the Earth, constituting about 80% of the inner and outer cores of Earth. The molten outer core is about $$8000$$ km in diameter, and the solid inner core is about 2400 km in diameter. Iron is plentiful because of its nuclear stability in stellar nuclear fusion reactions.

Titanium metal is a very durable metal for engineering applications because this metal is corrosion-resistant and also this metal is very strong and very light. It is $$40\% $$ lighter than steel but as strong as high-strength steel. So titanium finds applications in things like aerospace.

Iron and Titanium belongs to $$1st$$ transition series

$$\mathbf{Hence\ the\ correct\ answer\ is\ (A).}$$
Question 10
1 / -0

Which of the following is not the characteristic of transition metals?

A
They are all metals

B
They show variable oxidation states which always differ by two units

C
They are paramagnetic

D
They easily form complex

Solution

The $$d- block$$ elements that are the elements from a group $$3-12$$ are called transition elements. This is because their physical and chemical properties are intermediate between $$s-block$$ and $$p-block$$ properties. Hence these elements act as a bridge from $$s-block$$ to $$p-block$$ and hence they are known as transition

$$\mathbf{Characteristic\ of\ transition\ metals}$$

They have a large charge/radius ratio.
They are hard and have high densities.
They have high melting and boiling points.
They form compounds that are often paramagnetic.
They show variable oxidation states which differ by $$1$$ unit
They form coloured ions and compounds.
They form compounds with profound catalytic activity.
They form stable complexes.
All the transition elements are metals; this is because of the number of electrons in the outermost shell. Transition metals are hard, malleable, and ductile due to the presence of strong metallic bonds.

$$\mathbf{Hence\ the\ correct\ answer\ is\ (B)}$$

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Re-Attempt Weekly Quiz Competition

The d- and f- Block Elements Test - 47

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The d- and f- Block Elements Test - 47

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Question 1

overlapping of inner orbitals

free movement of electron over all the orbitals

small energy difference between $$5f$$ and $$6d$$ levels

none of above

Solution

Question 2

Decrease in density

Decreases in mass

Decrease in ionic radii

Decrease in radioactivity

Solution

Lanthanoid contraction effect results from poor shielding of nuclear charge (nuclear attractive force on electrons) by 4f electrons; the 6s electrons are drawn towards the nucleus, thus resulting in a smaller atomic radius.

Hence, option C is correct.

Question 3

in actinide series

in lanthanide series

in coinage metals

in alkaline earth metals

Solution

Question 4

$$ Yb^{3+} < Pm^{3+} < Ce^{3+} < La^{3+} $$

$$ Yb^{3+} < Pm^{3+} < La^{3+} < Ce^{3+} $$

$$ La^{3+} < Ce^{3+} < Yb^{3+} < Pm^{3+} $$

$$ Pm^{3+} < La^{3+} < Ce^{3+} < Yb^{3+}$$

Solution

Question 5

$$[Fe(CN)_6]^{3-}$$ is paramagnetic, $$[FeF_6]^{3-}$$ is diamagnetic

Both are diamagnetic

$$[Fe(CN)_6]^{3-}$$ is diamagnetic, $$[FeF_6]^{3-}$$ is paramagnetic

Both are paramagnetic

Solution

Question 6

$$[Co(CN)_6]^{3-}$$

$$[Fe(CN)_6]^{3-}$$

$$[Mn(CN)_6]^{3-}$$

$$[Cr(CN)_6]^{3-}$$

Solution

Question 7

$$ 1.40 \mathring{A}$$

$$ 1.06 \mathring{A}$$

$$ 0.85 \mathring{A} $$

$$ 1.60 \mathring{A} $$

Solution

Question 8

$$Hg_2Cl_2$$

$$PbCl_2$$

$$AgI$$

$$Cu(OH)_2$$

Solution

Question 9

first transition series

second transition series

third transition series

fourth transition series

Solution

Question 10

They are all metals

They show variable oxidation states which always differ by two units

They are paramagnetic

They easily form complex

Solution

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