The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 49

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Weekly Quiz Competition

Question 1
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In the dichromate dianion:

A
$$4Cr-O$$ bonds are equivalent

B
$$6Cr-O$$ bonds are equivalent

C
all $$Cr-O$$ bonds are equivalent

D
all $$Cr-O$$ bonds are non equivalent

Solution

Dichromate is a divalent inorganic anion obtained by removal of both protons from dichromic acid. It is a conjugate base of a hydrogen dichromate.
The dichromate ion consists of two tetrahedral sharing oxygen at the common corner. The six terminal bonds have the same bond length due to resonance

Hence, the correct option is B.
Question 2
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The colour of zinc sulphide is:

A
yellow

B
white

C
brown

D
black

Solution

Colour of zinc sulphide is white.
Question 3
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The correct order of ionic radii of $$Ce, La, Pm$$ and $$Yb$$ in $$+3$$ oxidation state is:

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

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

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

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

Solution

Order of radii:
$$Yb^{+3}< Pm^{+3} < Ce^{+3} < La^{+3}$$
Lanthanide contraction is the greater-than-expected decrease in ionic radii of the elements in the lanthanide series from atomic number 57, lanthanum, to 71, lutetium.
Due to Lanthanide contraction,Ionic radii decreases continously.
Question 4
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Which of the following pairs of ions is colourless?

A
$$Ti^{3+}, Cu^{2+}$$

B
$$Se^{3+}, Zn^{2+}$$

C
$$Co^{2+}, Fe^{3+}$$

D
$$Ni^{2+}, V^{3+}$$

Solution
Question 5
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Which of the following is not an actinide?

A
Curium

B
Californium

C
Uranium

D
Terbium

Solution

Elements after lanthanum i.e. from $$Ce$$ (atomic number $$58$$) to $$Lu$$ (atomic number $$71$$) are all lanthanides. The atomic number of Terbium is $$65$$ and hence it is a lanthanide, not an actinide.

Hence, the correct answer is option D.
Question 6
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Which of the following pairs of ions have same paramagnetic moment?

A
$$Mn^{2+}, Cu^{2+}$$

B
$$Cu^{2+}, Ti^{3+}$$

C
$$Ti^{4+}, Cu^{2+}$$

D
$$Ti^{3+}, Ni^{2+}$$

Solution

$$Cu^{2+}, Ti^{3+} $$ have the same number of unpaired electrons thus they will have same paramagnetic moment.
Question 7
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Among $$d-$$ block elements, the most abundant element belongs to the:

A
first transition series

B
second transition series

C
third transition series

D
fourth transition series

Solution

The most abundant transition metal is iron, which is fourth among all elements and second to aluminum in metals in abundance. Titanium, manganese, zirconium, vanadium, and chromium also have abundances in excess of 100 grams per 1000kg
Question 8
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Which one of the following ion has a magnetic moment of $$5.93\ B.M$$ ?

A
$$Mn^{2+}$$

B
$$Fe^{2+}$$

C
$$Cr^{2+}$$

D
$$V^{3+}$$

E
$$Cr^{3+}$$

Solution
Question 9
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Which has maximum paramagnetic character ?

A
$$[Fe(CN)_6]^{4-}$$

B
$$[Cu(H_2O)_4]^{2+}$$

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

D
$$[Mn(H_2O)_6]^{2+}$$

Solution

$$Mn^{+2}$$ has $$d^5$$ configuration with 5 unpaired electrons. Hence, it has the highest paramagnetic character.
Question 10
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Directions For Questions

The coordination number of $$Ni^{2+}$$ is $$4.$$

$$NiCl_{2} + KCN \longrightarrow A$$ (Cyano complex)

$$NiCl_{2} + Conc.\ HCl\ (excess) \longrightarrow B$$ (Chloro complex)

...view full instructions

Predict the magnetic nature of $$A$$ and $$B$$.

A
both are diamagnetic

B
$$A$$ is diamagnetic and $$B$$ is paramagnetic with one unpaired electrons

C
$$A$$ is diamagnetic and $$B$$ is paramagnetic with two unpaired electrons

D
both are paramagnetic

Solution

$$[Ni(CN)_4]^{2−}$$
The oxidation number of $$Ni$$ is $$+2$$.
Atomic number = 28
$$Ni = [Ar]3d^84s^2$$
$$Ni^{2+}=[Ar]3d^8$$
There are no unpaired electrons, so the complex is diamagnetic.

$$[NiCl_4]^{2−}$$
The oxidation number of $$Ni$$ is $$+2$$.
Atomic number = 28
$$Ni = [Ar]3d^84s^2$$
$$Ni^{2+}=[Ar]3d^8$$
Chloride is a weak field ligand, no pairing.
$$sp^3$$ hybridization (tetrahedral)
There are two unpaired electrons, so the complex is paramagnetic.

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The d- and f- Block Elements Test - 49

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The d- and f- Block Elements Test - 49

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SHARING IS CARING

Question 1

$$4Cr-O$$ bonds are equivalent

$$6Cr-O$$ bonds are equivalent

all $$Cr-O$$ bonds are equivalent

all $$Cr-O$$ bonds are non equivalent

Solution

Question 2

yellow

white

brown

black

Solution

Question 3

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

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

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

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

Solution

Question 4

$$Ti^{3+}, Cu^{2+}$$

$$Se^{3+}, Zn^{2+}$$

$$Co^{2+}, Fe^{3+}$$

$$Ni^{2+}, V^{3+}$$

Solution

Question 5

Curium

Californium

Uranium

Terbium

Solution

Question 6

$$Mn^{2+}, Cu^{2+}$$

$$Cu^{2+}, Ti^{3+}$$

$$Ti^{4+}, Cu^{2+}$$

$$Ti^{3+}, Ni^{2+}$$

Solution

Question 7

first transition series

second transition series

third transition series

fourth transition series

Solution

Question 8

$$Mn^{2+}$$

$$Fe^{2+}$$

$$Cr^{2+}$$

$$V^{3+}$$

$$Cr^{3+}$$

Solution

Question 9

$$[Fe(CN)_6]^{4-}$$

$$[Cu(H_2O)_4]^{2+}$$

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

$$[Mn(H_2O)_6]^{2+}$$

Solution

Question 10

both are diamagnetic

$$A$$ is diamagnetic and $$B$$ is paramagnetic with one unpaired electrons

$$A$$ is diamagnetic and $$B$$ is paramagnetic with two unpaired electrons

both are paramagnetic

Solution

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