The d- and f- Block Elements Test

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The d- and f- Block Elements Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

The electronic configuration of $$Co^{2+}$$ and $$Cu^{2+}$$ is $$d^7$$ and $$d^9$$ respectively,which of these ions is expecteed to be more paramagnetic ?

A
$$Co^{+2}$$

B
$$Cu^{2+}$$

C
Both have same

D
None of these

Solution

As we know,
$$\mu = \sqrt {n(n+2)}$$
where n = no of unpaired electron.
$$Co^{+2}$$ = more paramagnetic $$d^7 ; n = 3$$
$$Cu^{+2} = d^9 ; n = 1$$
Question 2
1 / -0

Which one of the following paramagnetic in nature?

A
$$CuCl_2$$

B
$$CaCl_2$$

C
$$CdCl_2$$

D
All of these

Solution

Option $$(A)$$ is correct.
In $$CuCl_2$$, $$Cu$$ is in +2 oxidation state.
Electronic configuration of $$Cu^{2+}$$ is $$[Ar], 3d^9$$, and is coloured and paramagnetic due to presence of an unpaired electron in the $$3d$$ sub-orbital.
Question 3
1 / -0

The chromate ion in acidic medium changes to ..............

A
$$CrO_4^{-2}$$

B
Cr$$_3$$O$$_{10}^{-2}$$

C
Cr$$_2$$O$$_7^{-2}$$

D
none of these

Solution

Option (C) is correct.
The chromate ion (yellow colour) in acidic medium changes to dichromate ion$$Cr_2O_7^{2-}$$ (orange - red colour). In alkaline medium, reverse happens.
In solution,the dichromate ions convert to chromate ions by the action of a base. Thus chromate ion and dichromate ion exists in equilibrium.
Question 4
1 / -0

Which of the following ion is not coloured ?

A
$$Ni(DMG)_2$$

B
$$[Co(SCN)_4]^{2-}$$

C
$$[Fe(H_2O)_5SCN]^{2+}$$

D
$$[Al(OH)_4]^-$$

Solution

$$[Al(OH)4]^-$$ is not colored because the transition of electrons is not possible in this.
Whereas, other are colored due to being transition metal complex have electrons in d orbitals and can undergo d-d transition hence can impart color.
Question 5
1 / -0

The transition metal used in X-rays tube is :

A
$$Mo$$

B
$$Ta$$

C
$$Tc$$

D
$$Pm$$

Solution

Among given metals, molybdenum is used in X-rays tube. In medical X-ray tubes the target is usually tungsten or a more crack-resistant alloy of rhenium (5%) and tungsten (95%), but sometimes molybdenum is used for more specialized applications, such as when softer X-rays are needed as in mammography.
Question 6
1 / -0

If each one of the above ionic species is in turn kept in a magnetic field, which one will get attracted ?

A
$$Co^{+2}$$

B
$$Mn^{+7}$$

C
$$Sc^{+3}$$

D
$$Ti^{+4}$$

Solution

$$Co^{+2} = [Ar]3d^7\,\,\,\,\,\,\,n = 3$$ attracted by a magnetic field due to presence of 3 unpaired electron.
Question 7
1 / -0

Raney nickel, which is used as a catalyst, is obtained:

A
by grinding solid nickel

B
by treating nickelaluminium alloy with dilute $$NaOH$$

C
by treating nickelaluminium alloy with dilute $$HCl$$

D
by heating nickel tetracarbonyl

Solution

Raney nickel, s solid catalyst composed of fine grains of a nickel Aluminium alloy which is used in many industrial process. It is obtained by treating nickel-Aluminium alloy with dilute $$NaOH$$.
Question 8
1 / -0

The tendency towards complex formation is maximum in:

A
s-block elements

B
p-block elements

C
d-block elements

D
none of the above

Solution

The tendency towards complex formation is maximum in $$d-block$$ elements as they have maximum vacant orbitals and thus shows variable oxidation state.
Question 9
1 / -0

The metal capable of gaining as well as losing an electron is:

A
Hg

B
Ca

C
Ag

D
Au

Solution

As shown in image, Gold has 2 electrons in level 1, 8 electrons in level 2, 18 in level 3, 32 in level 4, 18 in level 5 and 1 electron in level 6. Gold is having 1 eletcron in last level, so it can lost 1 electron to complete their valency or it can also gain 1 electron thus 2 electron will come in outer cell and will complete the last level.
Thus Option D is correct.
Question 10
1 / -0

Transitional elements exhibit variable valencies because they release electrons from the following orbits :

A
$$ns $$ orbit

B
$$ns$$ and $$ np $$ orbits

C
$$(n-1)d$$ and $$ns$$ orbits

D
$$(n-1)d$$ orbit

Solution

The ability of the transition metals to exhibit variable valency is generally attributed to the availability of more electrons in the $$(n-1)d$$ orbitals which are closer to the outermost $$ns$$ orbital in energy levels.

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Re-Attempt Weekly Quiz Competition

The d- and f- Block Elements Test - 29

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The d- and f- Block Elements Test - 29

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SHARING IS CARING

Question 1

$$Co^{+2}$$

$$Cu^{2+}$$

Both have same

None of these

Solution

Question 2

$$CuCl_2$$

$$CaCl_2$$

$$CdCl_2$$

All of these

Solution

Question 3

$$CrO_4^{-2}$$

Cr$$_3$$O$$_{10}^{-2}$$

Cr$$_2$$O$$_7^{-2}$$

none of these

Solution

Question 4

$$Ni(DMG)_2$$

$$[Co(SCN)_4]^{2-}$$

$$[Fe(H_2O)_5SCN]^{2+}$$

$$[Al(OH)_4]^-$$

Solution

Question 5

$$Mo$$

$$Ta$$

$$Tc$$

$$Pm$$

Solution

Question 6

$$Co^{+2}$$

$$Mn^{+7}$$

$$Sc^{+3}$$

$$Ti^{+4}$$

Solution

Question 7

by grinding solid nickel

by treating nickelaluminium alloy with dilute $$NaOH$$

by treating nickelaluminium alloy with dilute $$HCl$$

by heating nickel tetracarbonyl

Solution

Question 8

s-block elements

p-block elements

d-block elements

none of the above

Solution

Question 9

Hg

Ca

Ag

Au

Solution

Question 10

$$ns $$ orbit

$$ns$$ and $$ np $$ orbits

$$(n-1)d$$ and $$ns$$ orbits

$$(n-1)d$$ orbit

Solution

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