The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 51

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Weekly Quiz Competition

Question 1
1 / -0

Among the following, the species that is both paramagnetic and coloured is :

A
$$ \left [ MnO_{4} \right ]^{2-}$$

B
$$ \left [ TiCl_{6} \right ]^{2-}$$

C
$$ \left [ VO_{4} \right ]^{2-}$$

D
$$CrO_{2}Cl_{2}$$

Solution
Question 2
1 / -0

Which one of the following statements about lanthanides is false ?

A
Lanthanides are seperated from one another by ion exchange method

B
The ionic radii of trivalent lanthanides steadily increases with increase in atomic number

C
All lanthanides are highly dense metals

D
Most typical oxidation state of lanthanides is +3

Solution

The ionic radii of trivalent lanthanides steadily decreases with increase in
atomic number due to lanhanide contraction.
Question 3
1 / -0

The ions from among the following which are colourless are :
(i)$${Ti^{4+}} (ii){Cu^{+1}} (iii){Co^{3+}} (iv){Fe^{2+}}$$

A
(i) and (ii) only

B
(i),(ii) and (iii)

C
(iii) and (iv)

D
(ii) and (iii)

Solution

(i) Valence shell electron configuration of $${Ti^{4+}}$$ is $${3d^{0}{4s}^{0}}$$. As there is no unpaired electrons for d-d transition,the solution of will be colourless.
(ii) Valence shell electron configuration of $${Cu^{+}}$$$${3d^{10}{4s}^{0}}$$. As all electrons are transition , so the solution of ions will be colourless.
(iii) Valence shell electron configuration of $${Co^{3+}}$$ is $${3d^{6}}{4s^{0}}$$.As there are 4 unpaired electrons, there is d-d transition of electrons, so the solution of ions will be coloured.
(iv) Valence shell electron configuration of $${Fe^{2+}}$$ is $${3d^{6}}{4s^{0}}$$. As there are 4 unpaired electrons, there is d-d transition of electrons, so the solution of ions will be coloured.
Question 4
1 / -0

Which ionic radius of $${_{57}{La^{3+}}}$$ is 1.06A. which one of the following values will be closest to ionic radius of $${_{71}{Lu^{3+}}}$$. ?

A
1.06A

B
1.56A

C
0.85A

D
1.35A

Solution

Ionic radius of $${Lu{3+}}$$ is smaller than that of $${La{3+}}$$ because of lanthanide contraction across the period.
Question 5
1 / -0

Which of the following statements is wrong for the transition elements ?

A
Transition elements are placed from $$ 3^{rd}$$ to $$ 6^{th}$$ period

B
Last electron enters in (n-1) d orbital

C
Exhibits variable valency

D
General electronic configuration is (n-1) $$ d^{1-10}$$ $$ n s^{0-2}$$

Solution

Transition elements starts from $$4^{th}$$ period as they have valence shell configuration $$\left ( n-1 \right )d^{1-10}ns^{0-2}$$.

Option A is correct.
Question 6
1 / -0

Which one is false in the following statement

A
A catalyst is specific in its action

B
A very small amount of the catalyst alters the rate of a reaction

C
The number of free valencies on the surface of the catalyst increases on subdivision

D
Ni is used as catalyst in the manufacture of ammonia in the redox reaction

Solution

option D) is incorrect as in the manufacturing of ammonia, known as Born-Haber's cycle catalyst $$ Fe$$ is used not $$Ni$$.
Question 7
1 / -0

Which of the following types of metals forms the most efficient catalysts

A
Alkali metals

B
Alkaline earth metals

C
Transition metal

D
All of these

Solution

Transition metals can form unstable intermediate products with suitable reactants. These intermediate products lower the activation energy of the reaction which makes the reaction faster. So, transition elements are the most efficient catalysts.
Question 8
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Transition elements are coloured

A
Due to small size

B
Due to metallic nature

C
Due to unpaired d - electrons

D
All of these

Solution

Due to unpaired d-electrons transition elements are coloured.
Question 9
1 / -0

Transition metals are often paramagnetic owing to

A
Their high M.P. and B.P

B
The presence of vacant orbitals

C
The presence of one or more unpaired electrons in the system

D
Their being less electropositive than the elements of groups I-A and II-A

Solution

Transition metals are often paramagnetic owing to the presence of one or more unpaired electrons in the system.
Question 10
1 / -0

Which is not true for transition elements?

A
They are all metals

B
They show variable valency

C
They form coloured ions

D
They do not form co-ordinate compounds

Solution

Transition elements form co-ordinate compounds because of
(i) high nuclear charge
(ii) small size
(iii) vacant d-orbital.

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Re-Attempt Weekly Quiz Competition

The d- and f- Block Elements Test - 51

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The d- and f- Block Elements Test - 51

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Question 1

$$ \left [ MnO_{4} \right ]^{2-}$$

$$ \left [ TiCl_{6} \right ]^{2-}$$

$$ \left [ VO_{4} \right ]^{2-}$$

$$CrO_{2}Cl_{2}$$

Solution

Question 2

Lanthanides are seperated from one another by ion exchange method

The ionic radii of trivalent lanthanides steadily increases with increase in atomic number

All lanthanides are highly dense metals

Most typical oxidation state of lanthanides is +3

Solution

Question 3

(i) and (ii) only

(i),(ii) and (iii)

(iii) and (iv)

(ii) and (iii)

Solution

Question 4

1.06A

1.56A

0.85A

1.35A

Solution

Question 5

Transition elements are placed from $$ 3^{rd}$$ to $$ 6^{th}$$ period

Last electron enters in (n-1) d orbital

Exhibits variable valency

General electronic configuration is (n-1) $$ d^{1-10}$$ $$ n s^{0-2}$$

Solution

Question 6

A catalyst is specific in its action

A very small amount of the catalyst alters the rate of a reaction

The number of free valencies on the surface of the catalyst increases on subdivision

Ni is used as catalyst in the manufacture of ammonia in the redox reaction

Solution

Question 7

Alkali metals

Alkaline earth metals

Transition metal

All of these

Solution

Question 8

Due to small size

Due to metallic nature

Due to unpaired d - electrons

All of these

Solution

Question 9

Their high M.P. and B.P

The presence of vacant orbitals

The presence of one or more unpaired electrons in the system

Their being less electropositive than the elements of groups I-A and II-A

Solution

Question 10

They are all metals

They show variable valency

They form coloured ions

They do not form co-ordinate compounds

Solution

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