The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 50

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following pairs of transition metal ions are the stronger oxidising agents in aqueous solution?

A
$$V^{2+}$$ and $$Cr^{2+}$$

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

C
$$Mn^{3+}$$ and $$Co^{3+}$$

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

E
$$Ni^{2+}$$ and $$Fe^{2+}$$

Solution
Question 2
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In the long form of periodic table, all the non-metals and metalloids are placed with :

A
$$s$$-block

B
$$p$$-block

C
$$d$$-block

D
$$f$$-block

Solution

In the long form of the periodic table, all the non-metals and metalloids are placed $$p-block$$.

$$\mathbf{Hence\ the\ correct\ answer\ is\ option\ (B)}$$
Question 3
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The correct order of magnetic moments amongst following complex ions is:

A
$$[MnCl_4]^{2-} > [Fe(CN)_6]^{4-} > [CoCl_4]^{2-}$$

B
$$[Fe(CN)_6]^{4-}
> [MnCl_4]^{2-} > [CoCl_4]^{2-}$$

C
$$[MnCl_4]^{2-} > [CoCl_4]^{2-} > [Fe(CN)_6]^{4-}$$

D
$$[Fe(CN)_6]^{4-}
> [CoCl_4]^{2-} > [MnCl_4]^{2-} $$

Solution

Experimental evidence of magnetic measurements supports the theory of high- and low-spin complexes. Remember that molecules such as $$O_2$$ that contain unpaired electrons are paramagnetic. When an electron in an atom or ion is unpaired, the magnetic moment due to its spin makes the entire atom or ion paramagnetic.

$$Mn$$ is in a $$+2$$ oxidation state having configuration of $$[Ar]3d^5$$. It has $$5$$ unpaired electrons.

$$\mu = \sqrt{n(n+2)}= \sqrt{(5(5+2))}=5.9BM$$

The magnetic moment of $$[MnC1_4]^{2−}$$ is $$5.9 BM$$.

$$Co$$ is in $$+2$$ oxidation state having the configuration of $$[Ar]3d^7$$. It has $$3$$ unpaired electrons.

$$\mu = \sqrt{n(n+2)}= \sqrt{(3(3+2))}=3.9BM$$

Magnetic moment of $$[CoC1_4]^{2−}$$ is $$3.9 BM$$.

$$Fe$$ is in $$+2$$ oxidation state having the configuration of $$[Ar]3d^6$$. In this complex $$CN^−$$ ion is a strong ligand and all electrons are paired and there are no unpaired electrons.

$$\mu = \sqrt{n(n+2)} = \sqrt{(0(0+2))} =0BM$$

Magnetic moment of $$[FeCN_6]^{4-}$$ is $$0.0 BM.$$

$$\mathbf{\therefore [MnCl4]^{2−}>[CoCl4]^{2−}>[Fe(CN)6]^{4−}}$$

$$\mathbf{Hence\ the\ correct\ answer\ is\ option\ (C)}$$
Question 4
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Which one of the following complexes is not diamagnetic?

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

B
$$[Ti(H_2O)_6]^{3+}$$

C
$$[Pt(CN)_4]^{2-}$$

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

Solution

Complexes having unpaired electrons are $$Paramagnetic$$.
Complexes having paired electrons are $$Dimagnetic$$.

(i) $$[Fe(CN)_6]^{4-}$$
Fe oxidation state = +2 i.e. $$([Ar]3d^6)$$
$$CN^-$$ is a strong ligand and all 3d electrons in Fe gets paired.
$$[Fe(CN)_6]^{4-}$$ is low spin complex and $$d^2sp^3$$ hydridized.
Hence it is dimagnetic.

(ii) $$[Ti(H_2O)_6]^{3+}$$
Ti oxidation state = +3 i.e. $$([Ar]3d^1)$$
$$H_2O$$ is a weak field ligand and one unpaired electron is present in 3d orbital of Ti.
$$[Ti(H_2O)_6]^{3+}$$ is high spin complex and $$d^2sp^3$$ hydridized.
Hence it is paramagnetic.

(iii) $$[Pt(CN)_4]^{2-}$$
Pt oxidation state = +2 i.e. $$([Xe]5d^{10})$$
$$CN^-$$ is a strong ligand and all 5d electrons in Pt gets paired.
$$[Pt(CN)_4]^{2-}$$ is low spin complex and $$d^2sp$$ hydridized.
Hence it is dimagnetic.

(iv) $$[Co(NH_3)_6]^{3+}$$
Co oxidation state = +3 i.e. $$([Ar]3d^6)$$
$$NH_3$$ is a strong ligand and all 3d electrons in Co gets paired.
$$[Co(NH_3)_6]^{3+}$$ is low spin complex and $$d^2sp^3$$ hydridized.
Hence it is dimagnetic.

$$[Ti(H_2O)_6]^{3+}$$ is paramagnetic.
Therefore, the correct option is $$(B)$$.
Question 5
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The correct increasing order of paramagnetism of
$$(i)\ MnSO_4.
4H_2O$$
$$(ii)\ FeSO_4.
7H_2O$$
$$(iii)\ NiSO_4.
6H_2O$$
$$(iv)\ CuSO_4.
5H_2O$$ is:

A
$$(i) < (ii) < (iii) < (iv)$$

B
$$(iv) < (iii) < (i) < (i)$$

C
$$(iii) < (iv) < (ii) < (i)$$

D
$$(iii) < (iv) < (i) < (ii)$$

Solution

Paramagnetism depends on number of unpaired electrons. More the unpaired electrons, more will be paramagnetism.
(i) $$MnSO_4.4H_2O$$
Mn oxidation state = +2 i.e $$[Ar]3d^5$$
Number of unpaired electrons = 5

(ii)$$FeSO_4.7H_2O$$
Fe oxidation state = +2 i.e. $$[Ar]3d^6$$
Number of unpaired electrons = 4

(iii) $$NiSO_4.6H_2O$$
Ni oxidation state = +2 i.e. $$[Ar]3d^8$$
Number of unpaired electrons = 3

(iv) $$CuSO_4.5H_2O$$
Cu oxidation state = +2 i.e. $$[Ar]3d^9$$
Number of unpaired electrons = 1

Therefore, Increasing order of paramagnetism is
$$(iv)<(iii)<(ii)<(i)$$

Hence correct option is (B).
Question 6
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Transition metals form complexes because of:

A
small cation size

B
vacant $$d-$$ orbitals

C
large iconic charge

D
all of these

Solution
Question 7
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The statement that is not correct for the periodic classification of elements is:

A
The properties of elements are the periodic function of their atomic numbers

B
Non - metallic elements are lesser in number than metallic elements

C
The first ionisation energies of elements along a period do not vary in a regular manner with increase in atomic number

D
For transition elements the d subshells are filled with electrons monotonically with increase in atomic number

Solution

The d- sub shells are not filled with electrons monotonically with increase in atomic number.There are some exceptions like Cr,Cu etc.

Option D is correct.
Question 8
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The ionic radius of $$ _{57}La^{3+}$$ is 1.06 $$\overset oA$$ Which one the following give values will be closest to the ionic radius of $$ _{71}Lu^{3+}$$ ?

A
1.06 $$\overset oA$$

B
1.56 $$\overset oA$$

C
0.85 $$\overset oA$$

D
1.35 $$\overset oA$$

Solution
Question 9
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Which ine of the following statement about lanthanides is false?

A
Lanthanides are sepearated 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
Question 10
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Predict which pairs of ions is not coloured in aqueous solution ?

A
$$Ti^{3+} , V^{3+}$$

B
$$ Cu^{+},Sc^{3+}$$

C
$$ Cu^{2+},Fe^{2+}$$

D
$$ Co^{2+},Ni^{2+}$$

Solution

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The d- and f- Block Elements Test - 50

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The d- and f- Block Elements Test - 50

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Question 1

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

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

$$Mn^{3+}$$ and $$Co^{3+}$$

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

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

Solution

Question 2

$$s$$-block

$$p$$-block

$$d$$-block

$$f$$-block

Solution

Question 3

$$[MnCl_4]^{2-} > [Fe(CN)_6]^{4-} > [CoCl_4]^{2-}$$

$$[Fe(CN)_6]^{4-} > [MnCl_4]^{2-} > [CoCl_4]^{2-}$$

$$[MnCl_4]^{2-} > [CoCl_4]^{2-} > [Fe(CN)_6]^{4-}$$

$$[Fe(CN)_6]^{4-} > [CoCl_4]^{2-} > [MnCl_4]^{2-} $$

Solution

Question 4

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

$$[Ti(H_2O)_6]^{3+}$$

$$[Pt(CN)_4]^{2-}$$

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

Solution

Question 5

$$(i) < (ii) < (iii) < (iv)$$

$$(iv) < (iii) < (i) < (i)$$

$$(iii) < (iv) < (ii) < (i)$$

$$(iii) < (iv) < (i) < (ii)$$

Solution

Question 6

small cation size

vacant $$d-$$ orbitals

large iconic charge

all of these

Solution

Question 7

The properties of elements are the periodic function of their atomic numbers

Non - metallic elements are lesser in number than metallic elements

The first ionisation energies of elements along a period do not vary in a regular manner with increase in atomic number

For transition elements the d subshells are filled with electrons monotonically with increase in atomic number

Solution

Question 8

1.06 $$\overset oA$$

1.56 $$\overset oA$$

0.85 $$\overset oA$$

1.35 $$\overset oA$$

Solution

Question 9

Lanthanides are sepearated 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

Question 10

$$Ti^{3+} , V^{3+}$$

$$ Cu^{+},Sc^{3+}$$

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

$$ Co^{2+},Ni^{2+}$$

Solution

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$$[Fe(CN)_6]^{4-}
> [MnCl_4]^{2-} > [CoCl_4]^{2-}$$

$$[Fe(CN)_6]^{4-}
> [CoCl_4]^{2-} > [MnCl_4]^{2-} $$