Question Set A

CBSE 12th Standard Chemistry d- and f- Block Elements HOT Questions Study Material - QB365

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Questions:

Multiple Choice Question

45 x 1 = 45

Which of the following is a diamagnetic ion (atomic numbers of Sc, V, Mn and Cu are 21, 23, 25 and 29 respectively)

(a)

V²+

(b)

Sc³⁺

(c)

Cu²⁺

(d)

Mn³⁺

Which of the following transition metals does not show variable oxidation state?

(a)

(b)

(c)

(d)

The reason for greater range of oxidation state of actinoids is due to

(a)

actinoid contraction

(b)

Sf, 6d, 7s levels have comparable energies

(c)

4f and 5d levels are close in energies

(d)

the radioactive nature of actinoids

Which of the following statements related to lanthanoids is incorrect?

(a)

Eu shows + 2 oxidation state

(b)

Pr(OH)₃ to Lu(OH)₃, basicity decreases

(c)

All lanthanoids more reactive than Al

(d)

Ce⁴⁺ is used as oxidising agent

The oxidation state of Cr in final product formed by reaction of KI and acidified dichromate solution is

(a)

(b)

(c)

(d)

The stability of Mn²⁺, Fe²⁺,Cr²⁺, Co²⁺ is in order of (At o. of Mn = 25, Fe = 26, Cr = 24, Co = 27)

(a)

Mn²⁺ > Fe²⁺ > Cr²⁺ > CO²⁺

(b)

Fe²⁺ > Mn²⁺ > Co²⁺ > Cr²⁺

(c)

Co²⁺ > Mn²⁺ > Fe²⁺ > Cr²⁺

(d)

Cr²⁺ > Mn²⁺ > Co²⁺ > Fe²⁺

Acidified K₂Cr₂O₇ solution turns green when SO₂ gas is passed through it due to formation of

(a)

Cr₂(SO₄)₃

(b)

CrO₄^-2

(c)

Cr₂(SO₃)₃

(d)

CrSO₄

The number of moles of KMnO₄ that will be needed to react with one mole of SO₃^2- in acidic solution.

(a)

(b)

3/5

(c)

4/5

(d)

2/5

Which of the following is most stable in aqueous solution?

(a)

Mn²⁺

(b)

Cr³⁺

(c)

V³⁺

(d)

Ti³⁺

10.

Across the lanthanide series, the basicity of the lanthanide hydroxides

(a)

increases

(b)

decreases

(c)

first increases and then decreases

(d)

first decreases and then increases

11.

Transition elements have unique property that

(a)

they show variable oxidation state

(b)

these elements acts as catalyst

(c)

they form coloured compounds

(d)

All of the above

12.

Which of the following element show catalytic property?

(a)

(b)

(c)

(d)

None of these

13.

The equilibrium, Cr₂O^2-₇\( \rightleftharpoons \) 2CrO₄^2-is shifted to right in

(a)

an acidic medium

(b)

a basic medium

(c)

a neutral medium

(d)

it does not exist

14.

Which of the following pair of compounds is expected to exhibit same colour in aqueous solution ?

(a)

FeCI₂, CuCI₂

(b)

VOCI₂,CuCI₂

(c)

VOCI₂,FeCI₂

(d)

FeCI₂ , MnCI₂

15.

Which element out of the following do you expect to have the lowest melting point ?

(a)

(b)

(c)

(d)

16.

Which element do you expect to have the highest melting point ?

(a)

(b)

(c)

(d)

17.

Which element do you expect to have the smallest atomic radius ?

(a)

(b)

(c)

(d)

18.

Which of the following statements are correct when a mixture of NaCI and K₂Cr₂O₇ is gently warmed with conc. H₂SO₄ ?

(a)

a deep red vapour is evolved

(b)

The vapour when passed into NaOH solution gives yellow solution of Na₂CrO₄

(c)

chlorine gas is evolved

(d)

chromyl chloride is formed

19.

Potassium manganate (K₂MnO₄) is formed when

(a)

Chlorine is passed through aqueous KMnO₄ solution.

(b)

Manganese dioxide is fused with potassium hydroxide in air

(c)

Formaldehyde reacts with potassium permanganate in presence of strong alkali.

(d)

Potassium permanganate reacts with H₂SO₄.

20.

[Fe(H₂O)₅NO]²⁺ is a complex formed in the brown ring test for \({ NO }_{ 3 }^{ - }\) ion. In this complex

(a)

NO transfers its electron to Fe²⁺ so that we have iron as Fe(I) and NO as NO⁺

(b)

There are three unpaired electrons so that its magnetic moment is 3.87 B.M

(c)

The colour is due to charge transfer

(d)

All the above statements are correct.

21.

All Cu (II) halides are known except iodide. The reason for this is that

(a)

iodide ion is a bulky ion

(b)

Cu²⁺ oxidizes iodide to iodine

(c)

Cu²⁺ (aq) has much more negative hydration enthalpy

(d)

Cu²⁺ ion has smaller size.

22.

The actinoids exhibit more number of oxidation states in general than the lanthanoids. This is because

(a)

the 5f orbitals extend farther from the nucleus than the 4f orbitals

(b)

the 5f orbitals are more buried than the 4f orbitals

(c)

there is a similarity between 4f and 5f orbitals in their angular part of the wave function

(d)

the actinoids are more reactive than the lanthanoids

23.

In context of the lanthanoids, which of the following statements is not correct ?

(a)

All the members exhibit +3 oxidation state

(b)

Because of similar properties, the separation of lanthanoids is not easy.

(c)

Availability of 4f electrons results in the formation of compounds in +4 state for all the members of series.

(d)

There is a gradual decrease in the radii of the members with increasing atomic number in the series.

24.

Knowing that the chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect ?

(a)

The ionic sizes of Ln (III) decrease in general with increasing atomic number.

(b)

Ln (III) compounds are generally colourless.

(c)

Ln (III) hydroxides are mainly basic in character

(d)

Because of the large size of the Ln (III) ions, the bonding in its compounds is predominantly ionic in character.

25.

Which one of the following is the correct increasing order of the magnitude of ionic radii of Ce³⁺, La³⁺, Pm³⁺ and Yb³⁺?

(a)

\({ Yb }^{ 3+ }<{ Pm }^{ 3+ }<{ La }^{ 3+ }<{ Ce }^{ 3+ }\)

(b)

\({ Yb }^{ 3+ }<{ Pm }^{ 3+ }<{ Ce }^{ 3+ }<{ La }^{ 3+ }\)

(c)

\({ Pm }^{ 3+ }<{ La }^{ 3+ }<{ Ce }^{ 3+ }<{ Yb }^{ 3+ }\)

(d)

\({ Ce }^{ 3+ }<{ Yb }^{ 3+ }<{ Pm }^{ 3+ }<{ La }^{ 3+ }\)

26.

Lanthanide contraction is observed in

(a)

(b)

(c)

(d)

27.

Which of the following exhibits only +3 oxidation state ?

(a)

(b)

(c)

(d)

28.

In acidic medium, H₂O₂ changes \({ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }\) to CrO₅ which has two (-O-O-) bonds. Oxidation state of Cr in CrO₅ is

(a)

+ 5

(b)

+ 3

(c)

+ 6

(d)

- 10

29.

The colour of KMnO₄ is due to

(a)

\(L\rightarrow M \) charge transfer transition

(b)

\(\sigma \rightarrow { \sigma }^{ * }\) transition

(c)

\(M\rightarrow L\) charge transfer transition

(d)

\(d \rightarrow d\) transition.

30.

KMnO₄ gets reduced to

(a)

K₂MnO₄ in neutral medium

(b)

MnO₂ in acidic medium

(c)

Mn²⁺ in alkaline medium

(d)

MnO₂ in neutral medium

31.

A student accidently added conc . H₂SO₄ to potassium permanganate and it exploded due to the formation of an explosive which is

(a)

MnO

(b)

Mn₂O₃

(c)

Mn₂O₅

(d)

Mn₂O₇

32.

Identify the product and its colour when MnO₂ is fused with solid KOH in the presence of O₂

(a)

KMnO₄, purple

(b)

K₂MnO₄, dark green

(c)

MnO, colourless

(d)

Mn₂O₃, brown

(e)

MnO₂, black

33.

When hydrogen peroxide is added to acidified potassium dichromate, a blue colour is produced due to formation of

(a)

CrO₃

(b)

Cr₂O₃

(c)

CrO₅

(d)

\({ CrO }_{ 4 }^{ 2- }\)

(e)

\({ CrO }_{ 7 }^{ 2- }\)

34.

Among the oxides, Mn₂O₇ (I), V₂O₃(II),V₂O₅ (III),CrO (IV) and Cr₂O₃ (V), the basic oxides are

(a)

I and II

(b)

II and III

(c)

III and IV

(d)

II and IV

(e)

III and V

35.

The titanium (atomic number 22) compound that does not exist is

(a)

TiO

(b)

TiO₂

(c)

K₂TiF₆

(d)

TiCI₃

(e)

K₂TiO₄

36.

The number of unpaired electrons in gaseous species of Mn³⁺. Cr³⁺ and V³⁺ respectively are ........ and most stable species is ......... .

(a)

4,3 and 2 and V³⁺ is most stable

(b)

3,3 and 2 and Cr³⁺ is most stable

(c)

4,3 and 2 and Cr³⁺ is most stable

(d)

3,3 and 3 and Mn³⁺ is most stable.

37.

Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids?

(a)

(b)

(c)

(d)

38.

Which of the following actinoids show oxidation states upto +7 ?

(a)

(b)

(c)

(d)

39.

Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured ?

(a)

KMnO₄

(b)

Ce(SO₄)₂

(c)

TiCI₄

(d)

Cu₂CI₂

40.

When KMnO₄ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because

(a)

CO₂ is formed as the product

(b)

Reaction is exothermic

(c)

\({ MnO }_{ 4 }^{ - }\) catalyses the reaction

(d)

Mn²⁺ acts as autocatalyst

41.

The magnetic nature of elements depends on the presence of unpaired electrons, Identify the configuration of transition element, which shows highest magnetic moment.

(a)

3d⁷

(b)

3d⁵

(c)

3d⁸

(d)

3d²

42.

KMnO₄, oxidation number of Mn is

(a)

+ 2

(b)

+ 4

(c)

+ 6

(d)

+ 7

43.

In the reaction : \(NaCI+{ K }_{ 2 }{ Cr }_{ 2 }{ O }_{ 7 }+conc.{ H }_{ 2 }{ SO }_{ 4 }\underrightarrow { heat } X+{ Na }_{ 2 }{ SO }_{ 4 }+{ K }_{ 2 }{ SO }_{ 4 }+{ H }_{ 2 },X\) is a raddish brown gas which gives a yellow solution on passing through water and a yellow precipitate on treating the solution with lead acetate solution X could be

(a)

CI₂

(b)

CrO₃

(c)

H₂CrO₄

(d)

CrO₂CI₂

44.

Which of the following statement about transition elements is incorrect ?

(a)

They show variable oxidation states

(b)

All the ions are coloured

(c)

They exhibit diamagnetic and paramagnetic properties

(d)

They exhibit catalytic property

45.

Which metal has highest density ?

(a)

(b)

(c)

(d)

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Answers Key:

Multiple Choice Question

45 x 1 = 45

(b)
Sc³⁺

(d)
Sc

(b)
Sf, 6d, 7s levels have comparable energies

(d)
+3

(a)
Mn²⁺ > Fe²⁺ > Cr²⁺ > CO²⁺

(a)
Cr₂(SO₄)₃

(d)
2/5

(b)
Cr³⁺

10.

(b)
decreases

11.

(d)
All of the above

12.

(b)
Fe

13.

(b)
a basic medium

14.

(b)
VOCI₂,CuCI₂

15.

(b)
Mn

16.

(b)
W

17.

(b)
Zn

18.

(a)
a deep red vapour is evolved

19.

(b)
Manganese dioxide is fused with potassium hydroxide in air

20.

(d)
All the above statements are correct.

21.

(b)
Cu²⁺ oxidizes iodide to iodine

22.

(a)
the 5f orbitals extend farther from the nucleus than the 4f orbitals

23.

24.

(b)
Ln (III) compounds are generally colourless.

25.

(b)
\({ Yb }^{ 3+ }<{ Pm }^{ 3+ }<{ Ce }^{ 3+ }<{ La }^{ 3+ }\)

26.

(a)
Gd

27.

(a)
Ac

28.

29.

(a)
\(L\rightarrow M \) charge transfer transition

30.

(a)
K₂MnO₄ in neutral medium

31.

(d)
Mn₂O₇

32.

(b)
K₂MnO₄, dark green

33.

34.

(d)
II and IV

35.

(e)
K₂TiO₄

36.

37.

38.

(d)
Np

39.

(a)
KMnO₄

40.

(d)
Mn²⁺ acts as autocatalyst

41.

(b)
3d⁵

42.

(d)
+ 7

43.

(d)
CrO₂CI₂

44.

(b)
All the ions are coloured

45.

(b)
Os

CBSE 12th Standard Chemistry d- and f- Block Elements HOT Questions Study Material - QB365 Set A

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Std: 12th Standard CBSE - Chemistry

chapter: d- and f- Block Elements - HOT Questions

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