The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 74

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Weekly Quiz Competition

Question 1
1 / -0

Which one of the following characteristics of the transition metals is associated with their catalytic activity?

A
Variable oxidation states

B
High enthalpy of atomization

C
Paramagnetic behaviour

D
Colour of hydrated ions

Solution

The transition metals form the reaction intermediates due to the presence of vacant orbitals or their tendency to form variable oxidation states.
Question 2
1 / -0

The magnetic moment of a metal ion of first transition series is 2.83 BM. Therefore it will have unpaired electrons

A
6

B
4

C
3

D
2

Solution

$$ \mu = \sqrt { n(n+2) } \quad ( \mu $$ = magnetic moment)

where, n. no. of unpaired electron.

$$ 2.83 = \sqrt { n(n+2) } $$

$$ n(n+2) = 8 $$

$$ n^2 +2n - 8 = 0 $$

$$ n = 2 $$
Question 3
1 / -0

Which of the following may be colourless?

A
$$ Cr^{3+} $$

B
$$ Cu^{+} $$

C
$$ Fe^{3+} $$

D
$$ Cu^{2+} $$

Solution

$$ Cu^{+} $$ may be colourless due to completely filled d-orbitals.
Question 4
1 / -0

Which of the following pair of ions may exhibit same colour?

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

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

C
$$ Fe^{+++} $$ and $$ Mn^{++} $$

D
$$ Cu^+ $$ and $$ Ni^{++} $$

Solution

$$ Cr^{+++} $$ and $$ Fe^{++} $$ is the pair of ions which exhibit almost the same colour

$$ Cr^{3+} \rightarrow green $$

$$ Fe^{2+} \rightarrow pale-green $$
Question 5
1 / -0

Which one of the following ions is colourless?

A
$$ Cu^+ $$

B
$$ Co^{2+} $$

C
$$ Ni^{2+} $$

D
$$ Fe^{3+} $$

Solution

$$ Cu^+ $$ ion is colourless as it has no unpaired electrons.

$$ Cu^+ - [Ar]3d^{10} 4s^0 $$
Question 6
1 / -0

Which of the following ions has the highest magnetic moment?

A
$$ Ti^{3+} $$

B
$$ Sc^{3+} $$

C
$$ Mn^{2+} $$

D
$$ Zn^{2+} $$

Solution

$$ Ti^{3+} \rightarrow [Ar]3d^1 4s^0 ; \ Sc^{3+} \rightarrow [Ar]3d^0 $$

$$ Mn^{2+} \rightarrow [Ar]3d^5 4s^0; \ Zn^{2+} \rightarrow [Ar]3d^{10} 4s^0 $$

In $$ Mn^{2+} \rightarrow $$ number of unpaired electrons $$= 5. $$

So it has maximum magnetic moment according to the formula $$ \mu = \sqrt { n( n+2)} $$
Question 7
1 / -0

In nitroprusside ion, the iron and $$NO$$ exist as $$ Fe^{II} $$ and $$ NO^+ $$ rather than $$ Fe^{III } $$ and $$ NO $$. These forms can be differentiated by

A
Estimating the concentration of iron

B
Measuring the concentration of $$ CN^- $$

C
Measuring the solid state magnetic moment

D
Thermally decomposing the compound

Solution

The existence of $$ Fe^{2+} $$ and $$ NO^+ $$ in Nitroprusside ion $$ [Fe(CN)_5NO]^{2-} $$ can be established by measuring the magnetic moment of the solid compound which should correspond to $$ (Fe^{2+} = 3d^6 ) $$ four unpaired electrons.
Question 8
1 / -0

Which of the following trivalent ion has the largest atomic radii in the lanthanide series?

A
$$ La $$

B
$$ Ce $$

C
$$ Pm $$

D
$$ Lu $$

Solution

Lanthanum is the first and repesentative element of Lanthanide series and size decreases with increase in atomic number. So, $$La$$ has the largest atomic radii.
Question 9
1 / -0

Which of the following is paramagnetic?

A
$$ Ni^{2+} $$

B
$$ Cu^{+} $$

C
$$ Zn^{2+} $$

D
$$ Sc^{3+} $$

Solution

Elements or ions containing unpaired electrons are paramagnetic.

$$ _{28}Ni = [Ar] 3d^8 4s^2;\quad Ni^{2+} = [Ar] 3d^8 4s^0 $$

Because $$ Ni^{2+} $$ have 2 unpaired electrons in 3d subshell therefore it is paramagnetic.
Question 10
1 / -0

A copper salt is isomorphic with $$ ZnSO_4 $$, the salt will be

A
paramagnetic

B
diamagnetic

C
ferromagnetic

D
none

Solution

$$ ZnSO_4 \rightarrow Zn^{2+} + SO^{2-}_4 $$

Isomorphic with $$ Zn^{2+} \approx Cu^{2+} $$

$$ Cu^{2+} \rightarrow [Ar]3d^9 - 1 $$ unpaired electron.

$$ \therefore $$ Paramagnetic in nature

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Re-Attempt Weekly Quiz Competition

The d- and f- Block Elements Test - 74

Result

The d- and f- Block Elements Test - 74

Score

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SHARING IS CARING

Question 1

Variable oxidation states

High enthalpy of atomization

Paramagnetic behaviour

Colour of hydrated ions

Solution

Question 2

6

4

3

2

Solution

Question 3

$$ Cr^{3+} $$

$$ Cu^{+} $$

$$ Fe^{3+} $$

$$ Cu^{2+} $$

Solution

Question 4

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

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

$$ Fe^{+++} $$ and $$ Mn^{++} $$

$$ Cu^+ $$ and $$ Ni^{++} $$

Solution

Question 5

$$ Cu^+ $$

$$ Co^{2+} $$

$$ Ni^{2+} $$

$$ Fe^{3+} $$

Solution

Question 6

$$ Ti^{3+} $$

$$ Sc^{3+} $$

$$ Mn^{2+} $$

$$ Zn^{2+} $$

Solution

Question 7

Estimating the concentration of iron

Measuring the concentration of $$ CN^- $$

Measuring the solid state magnetic moment

Thermally decomposing the compound

Solution

Question 8

$$ La $$

$$ Ce $$

$$ Pm $$

$$ Lu $$

Solution

Question 9

$$ Ni^{2+} $$

$$ Cu^{+} $$

$$ Zn^{2+} $$

$$ Sc^{3+} $$

Solution

Question 10

paramagnetic

diamagnetic

ferromagnetic

none

Solution

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