The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 75

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following pair will have effective magnetic moment equal?

A
$$ Cr^{3+} $$ and $$ Mn^{2+} $$

B
$$ Cr^{2+} $$ and $$ Fe^{2+} $$

C
$$ V^{2+} $$ and $$ Sc^{3+} $$

D
$$ Ti^{2+} $$ and $$ V^{2+} $$

Solution

$$ Cr^{2+} $$ and $$ Fe^{2+ }$$ will have an effective magnetic moment equal since they have the same number of unpaired electrons.

$$ Cr^{2+} - [Ar]3d^4 \to$$ 4 unpaired electrons

$$ Fe^{2+} - [Ar]3d^6\to $$ 4 unpaired electrons
Question 2
1 / -0

Which of the following weighs less when weighed in magnetic field?

A
$$ VCl_3 $$

B
$$ ScCl_3 $$

C
$$ TiCl_3 $$

D
$$ FeCl_3 $$

Solution

$$ ScCl_3 \rightarrow Sc^{3+} + 3Cl^- $$

$$ScCl_3$$ has no unpaired electron so will show diamagnetic character and will be repelled, so will weigh less.
Question 3
1 / -0

Which of the following is more paramagnetic?

A
$$ Fe^{2+} $$

B
$$ Fe^{3+} $$

C
$$ Cr^{3+} $$

D
$$ Mn^{3+} $$

Solution

$$ Fe^{3+} \to [Ar]3d^5\to $$ having 5 unpaired electrons have the highest number of unpaired electrons so it will be more paramagnetic.
Question 4
1 / -0

Effective magnetic moment of $$ Sc^{3+} $$ ion is

A
1.73

B
0

C
5.92

D
2.83

E
3.87

Solution

Magnetic moment, $$\mu=\sqrt{n(n+2)}$$

Where $$n =$$ number of unpaired electrons

For $$ Sc^{3+} = [Ar]3d^0 , \quad n = 0 , \quad \therefore \mu = 0 $$
Question 5
1 / -0

$$ V_2O_5 $$ is useful as catalyst in

A
manufacturing of $$ H_2SO_4 $$

B
manufacturing of $$ HNO_3 $$

C
manufacturing of $$ Na_2CO_3 $$

D
it is not a catalyst

Solution

$$ V_2O_5 $$ is useful as catalyst in manufacturing of $$ H_2SO_4 $$
Hene, Option "A" is the correct answer.
Question 6
1 / -0

Which of the following will show increase in weight when kept in magnetic field?

A
$$ TiO_2 $$

B
$$ Fe_2(SO_4)_3 $$

C
$$ KMnO_4 $$

D
$$ ScCl_3 $$

Solution

$$ Fe_2(SO_4)_3 \to Fe^{3+} -[Ar]3d^5 - 5$$ electrons are unpaired. So, Fe will be attracted in the magnetic field so it will show an increase in weight.
Question 7
1 / -0

Which one of the following is expected to be paramagnetic complex?

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

B
$$[Ni(CO)_4]$$

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

D
$$[Co(NH_3)_6]^{3+}$$

Solution

The configuration of $$Ni^{2+}$$ in $$[Ni(H_2O)_6]^{2+}$$ has two unpaired electrons so it is paramagnetic.

$$[Ni(H_2O)_6]^{2+}\to Ni^{2+}\to [Ar]3d^8\to$$ two unpaired electrons in the complex.
Question 8
1 / -0

$$ [Sc(H_2O)_6]^{3+} $$ ion is

A
colourless and diamagnetic

B
coloured and octahedral

C
colourless and paramagnetic

D
coloured and paramagnetic

Solution

$$ [Sc(H_2O)_6]^{3+} \to\ _{21}Sc = [Ar] 3d^1 4s^2 $$

$$ Sc^{3+}= [Ar]3d^0 4s^0 \to $$ no unpaired electrons in d subshell, so it is diamagnetic and colourless and because of the six ligand it is octahedral in shape.
Question 9
1 / -0

Which of the following statement is not true?

A
Colourless compounds of transition elements are paramagnetic

B
Coloured compounds of transition elements are paramagnetic

C
Colourless compounds of transition elements are diamagnetic

D
Transition elements form the complex compounds

Solution

Colourless compounds are those which have no unpaired electrons and paramagnetic substance do have unpaired electrons. Therefore paramagnetic substances possess colour.
Question 10
1 / -0

Which of the following is the green coloured powder is produced when ammonium dichromate is used in fireworks?

A
$$ Cr $$

B
$$ CrO_3 $$

C
$$ Cr_2O_3 $$

D
$$ CrO(O_2) $$

Solution

The green coloured powder is produced when ammonium dichromate is used in fireworks is $$ Cr_2O_3 .$$

$$ (NH_4)_2Cr_2O_7 \quad \xrightarrow { \Delta} \quad Cr_2O_3 +N_2+4H_2O$$

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Re-Attempt Weekly Quiz Competition

The d- and f- Block Elements Test - 75

Result

The d- and f- Block Elements Test - 75

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SHARING IS CARING

Question 1

$$ Cr^{3+} $$ and $$ Mn^{2+} $$

$$ Cr^{2+} $$ and $$ Fe^{2+} $$

$$ V^{2+} $$ and $$ Sc^{3+} $$

$$ Ti^{2+} $$ and $$ V^{2+} $$

Solution

Question 2

$$ VCl_3 $$

$$ ScCl_3 $$

$$ TiCl_3 $$

$$ FeCl_3 $$

Solution

Question 3

$$ Fe^{2+} $$

$$ Fe^{3+} $$

$$ Cr^{3+} $$

$$ Mn^{3+} $$

Solution

Question 4

1.73

0

5.92

2.83

3.87

Solution

Question 5

manufacturing of $$ H_2SO_4 $$

manufacturing of $$ HNO_3 $$

manufacturing of $$ Na_2CO_3 $$

it is not a catalyst

Solution

Question 6

$$ TiO_2 $$

$$ Fe_2(SO_4)_3 $$

$$ KMnO_4 $$

$$ ScCl_3 $$

Solution

Question 7

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

$$[Ni(CO)_4]$$

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

$$[Co(NH_3)_6]^{3+}$$

Solution

Question 8

colourless and diamagnetic

coloured and octahedral

colourless and paramagnetic

coloured and paramagnetic

Solution

Question 9

Colourless compounds of transition elements are paramagnetic

Coloured compounds of transition elements are paramagnetic

Colourless compounds of transition elements are diamagnetic

Transition elements form the complex compounds

Solution

Question 10

$$ Cr $$

$$ CrO_3 $$

$$ Cr_2O_3 $$

$$ CrO(O_2) $$

Solution

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