Question Set B

CBSE 12th Chemistry d- and f- Block Elements Important Questions And Answers Study Material - QB365

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Questions:

Generic 2

6 x 2 = 12

Give two physical properties of aUoy formed by transition metals.

State reason for each of the following
(i) CO is stronger complexing reagent than NH₃
(ii) The molecular shape of Ni(CO)₄ is not the same as that of [Ni(CN)₄]^2-

Give an example of ion is at ion isomerism.

Which out of \(Lu(OH_{ 3 })\) and \(La(OH)_{ 3 }\) is more basic and why?

Arrange the following is increasing order of their solubility in water
C₆H₅NH₂, (C₂H₅)₂NH, C₂H₅NH₂

Why do amines react as nucleophiles?

Generic 3

6 x 3 = 18

Identify A, B and C in the following reactions.
\(\begin{equation} \text { (i) } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl} \stackrel{\mathrm{KCN}}{\longrightarrow} A \stackrel{\mathrm{H}_{2} / \mathrm{Ni}}{\longrightarrow} B \stackrel{\mathrm{CH}_{3} \mathrm{COCl} / \text { Base }}{\longrightarrow} C \end{equation}\)
\(\begin{equation} \text { (ii) } \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}^{+} \mathrm{Cl}^{-} \stackrel{\mathrm{HBF}_{4}}{\longrightarrow} A \end{equation}\) \(\xrightarrow[{\triangle }]{NaNO2/Cu}\)B\(\begin{equation} \stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} C \end{equation}\)

The E^O value in respect of electrodes of chromium (Z = 24), manganese (Z = 25) and iron (Z = 26) are Cr³⁺ /Cr²⁺ = - 0.4 V ; Mn³⁺ / Mn²⁺= : 1.5 V Fe³⁺ / Fe²⁺= + 0.8 V. On the basis of the above information, compare the feasibilities of further oxidation of their +2 oxidation state.

(a) How would you account for the following?
(i) Highest fluoride of Mn is MnF₄ whereas the highest oxide is Mn₂O₇.
(ii) Transition metals and their compounds show catalytic properties.
(b) Complete the following equation:
3MnO₄^2- + 4H⁺ ⟶

10.

Write the IUPAC name and draw the structure of each of the following complex entities:
(i)

(ii) [PtCl₃(C₂H₄)]Cl₂
(Atomic no. of Cr = 25, Co = 27, Pt = 78)

11.

(i) What type of isomerism is shown by the complex [Cr(H₂O)₆]Cl₃?
(ii) On the basis of crystal field theory, write the electronic configuration for d⁴ ion if \({ \triangle }_{ 0 }
(iii) Write the hybridization and shape of [CoF₆]^3- (Atomic number of Co = 27)

12.

Two isomeric compounds A and B having molecular formula C₄H₁₁N, both lose N₂on treatment with HNO₂ and gives compound C and D respectively. C is resistant to oxidation but immediately responds to Lucas reagent, where as 'D' responds to Lucas reagent after 5 minutes and gives a positive iodoform test. Identify A and B.

Multiple Choice Question

40 x 1 = 40

13.

The formula of the complex dichloridobis (ethane-1, 2-diamine) platinum (IV) nitrate is

(a)

[PtCl₂(en)₂(NO₃)₂]

(b)

[PtCl₂(en)₂] (NO₃)₂

(c)

[PtCl₂(en)₂(NO₃)] NO₃

(d)

[Pt(en)₂(NO₃)₂] Cl₂

14.

How many ions are produced from the complex [Co(NH₃)₅Cl] Cl₂ in solution?

(a)

(b)

(c)

(d)

15.

Name the gas that can readily decolourised by acidified KMnO₄ solution.

(a)

SO₂

(b)

NO₂

(c)

P₂O₅

(d)

CO₂

16.

CO is stronger ligand than Cl^- because

(a)

CO is neutral molecule

(b)

CO has \(\pi\)-bond

(c)

CO is poisonous

(d)

CO is more reactive

17.

Which ofthe following lanthanoid ion is diamagnetic? (At No. of Ce = 58, Sm = 62, Eu = 63 Yb = 70)

(a)

Eu²⁺

(b)

Yb²⁺

(c)

Ce²⁺

(d)

Sm²⁺

18.

Consider the following figure.

Which type of bond formed between metal and ligand?

(a)

synergic bond

(b)

σ-bond

(c)

ㅠ-bond

(d)

None of these

19.

In [Fe(CN)₆]^4- and [Fe(CN)₆]^3- number of unpaired electrons is, respectively

(a)

4,5

(b)

0,1

(c)

5,4

(d)

1,2

20.

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

21.

Reduction of the metal centre in aqueous permanganate ion involves.

(a)

3 electrons in neutral medium

(b)

5 electrons in neutral medium

(c)

3 electrons in alkaline medium

(d)

5 electron in acidic medium

22.

Transition elements have greater tendency to form complexes because

(a)

They have vacant d orbitals

(b)

They have large size

(c)

They have large charge/ size ratio

(d)

They have two electrons in their outermost shells

23.

Pick out the correct statements from the following
1. Cobalt (III) is more stable in octahedral complexes.
2. Zinc forms coloured ions or complexes.
3. Most of the d - block elements and their compounds are ferromagnetic.
4. Osmium shows (VIII) oxidation state.
5. Cobalt (II) is more stable in octahedral complexes.

(a)

1 and 2

(b)

1 and 3

(c)

2 and 4

(d)

1 and 4

(e)

2 and 5

24.

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)

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

25.

Gadolinium belongs to 4 f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium ?

(a)

[Xe]4 f ⁹ 5 s ¹

(b)

[Xe] 4 f ⁷ 5 d¹ 6 s²

(c)

[Xe] 4 f ⁶ 5 d² 6 s²

(d)

[Xe] 4 f ⁸6 d²

26.

In which of the following ions, the colour is not due to d - d transition ?

(a)

\({ Ti(H }_{ 2 }{ O) }_{ 6 }^{ 3+ }\)

(b)

\({ CoF }_{ 6 }^{ 3- }\)

(c)

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

(d)

\([{ Cu(NH }_{ 3 })_{ 4 }]^{ 2+ }\)

27.

K₂Cr₂O₇ reacts with NH₄CI in presence of H₂SO₄. The product formed is

(a)

chromyl chlorate with green vapour

(b)

chromous chloride with white vapour

(c)

chromous chloride with blue vapour

(d)

chromyl chloride with deep red colour

28.

The colour of the light absorbed by an aqueous solution of CuSO₄ is

(a)

orange - red

(b)

blue - green

(c)

yellow

(d)

violet

29.

Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment ?

(a)

Co²⁺

(b)

Cr²⁺

(c)

Mn²⁺

(d)

Cr³⁺

30.

Although Zirconium belongs to 4d transition series and Hafnium to 5d transition series even then they show similar physical and chemical properties because ........... .

(a)

both belong to d - block

(b)

both have same number of electrons

(c)

both have similar atomic radius

(d)

both belong to the same group of the periodic table

31.

Highest oxidation state of manganese in fluoride is +4 (MnF₄) but highest oxidation state in oxides is +7 (Mn₂O₇ ) because ............ .

(a)

fluorine is more electronegative than oxygen

(b)

fluorine does not possess d - orbitals

(c)

fluorine stabilise lower oxidation state

(d)

in covalent compounds, fluorine can form single bond only while oxygen forms double bond

32.

KMnO₄ acts as an oxidising agent in acidic medium. The number of moles of KMnO₄ that will be needed to react with one mole of sulphide ions in acidic solution is

(a)

\(\frac { 2 }{ 5 } \)

(b)

\(\frac { 3 }{ 5 } \)

(c)

\(\frac { 4 }{ 5 } \)

(d)

\(\frac { 1 }{ 5 } \)

33.

Which of the following reactions are disproportionation reactions?
\((i)\ { Cu }^{ + }\longrightarrow { Cu }^{ 2+ }+{ Cu }\)
\((ii)\ { 3MnO }_{ 4 }^{ - }+{ 4H }^{ + }\longrightarrow { 2MnO }_{ 4 }^{ - }+{ MnO }_{ 2 }+{ 2H }_{ 2 }O\)
\((iii)\ { 2KMnO }_{ 4 }\longrightarrow { K }_{ 2 }{ MnO }_{ 4 }+{ MnO }_{ 2 }+{ O }_{ 2 }\)
\((iv)\ { 2MnO }_{ 4 }^{ - }+{ 3Mn }^{ 2+ }+{ 2H }_{ 2 }O\longrightarrow { 5MnO }_{ 2 }+{ 4H }^{ + }\)

(a)

(i),(ii)

(b)

(i),(ii),(iii)

(c)

(ii),(iii),(iv)

(d)

(i),(iv)

34.

Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state ?

(a)

Ag₂SO₄

(b)

CuF₂

(c)

ZnF₂

(d)

Cu₂CI₂

35.

The colour of the coordination compounds depends on the crystal field splitting. What will be the correct order of absorption of wavelength of light in the visible region for the complexes, [Co(NH₃)₆]³⁺, [Co(CN)₆]^3-, [Co(H₂O)₆]³⁺

(a)

[Co(CN)₆]^3- > [Co(NH₃)₆]³⁺ > [Co(H₂O)₆]³⁺

(b)

[Co(NH₃)₆]³⁺ > [Co(H₂O)₆]³⁺ > [Co(CN)₆]^3-

(c)

[Co(H₂O)₆]³⁺ > [Co(NH₃)₆]³⁺ > [Co(CN)₆]^3-

(d)

[Co(CN)₆]^3- > [Co(NH₃)₆]³⁺ > [Co(H₂O)₆]³⁺

36.

The compound Na₂[Fe(CN)₅NO] is called

(a)

sodium nitroprusside

(b)

sodium pentacyanonitrosonium ferrate (II)

(c)

sodium pentacyanonitrosylferrate (III)

(d)

sodium nitrosoferrocyanide

37.

In nitroprusside ion, 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

38.

When excess ammonia is added to CuSo₄ solution, the deep blue complex obtained is

(a)

tetrahedral and paramagnetic

(b)

tetrahedral and diamagnetic

(c)

square planar and diamagnetic

(d)

square planar and paramagnetic

(e)

tetrahedral and ferromagnetic

39.

Which of the following complexes is used as an anti-cancer agent?

(a)

mer-[Co(NH₃)₃Cl₃]

(b)

cis-[PtCl₂(NH₃)₂]

(c)

cis-K₂[PtCl₂Br₂]

(d)

Na₂CoCl₄

40.

How many EDTA (ethylenediaminetetraacetic acid) molecules are required to make an octahedral complex with a Ca²⁺ ion?

(a)

One

(b)

Two

(c)

Six

(d)

Three

41.

[Cr(H₂O)₆]Cl₃ (at.no. of Cr = 24) has a magnetic moment of 3.83 B.M. The correct distribution of 3d electrons in the chromium of the complex is

(a)

\({ 3d }_{ xy }^{ 1 },{ 3d }_{ yz }^{ 1 },{ 3d }_{ xz }^{ 1 }\)

(b)

\({ 3d }_{ xy }^{ 1 },{ 3d }_{ yz }^{ 1 },{ 3d }_{ z ^2}^{ 1 }\)

(c)

\({ 3d }_{ (x^2-y^2)}^{ 1 },{ 3d }_{ z^2 }^{ 1 },{ 3d }_{ xz }^{ 1 }\)

(d)

\({ 3d }_{ xy}^{ 1 },{ 3d }_{ (x^2-y^2) }^{ 1 },{ 3d }_{ yz }^{ 1 }\)

42.

The hybridization involved in the complex [Ni(CN)₄]^2- is (At.No. of Ni=28)

(a)

d²sp²

(b)

d²sp³

(c)

dsp²

(d)

sp³

43.

The complex which has the highest magnetic moment among the following is

(a)

[CoF₆]^3-

(b)

[Co(NH₃)₆]³⁺

(c)

[Ni(NH₃)₄]²⁺

(d)

[Ni(CN)₄]^2-

(e)

[Fe(CN)₆]^4-

44.

The two isomers X and Y with the formula Cr(H₂O)₅ClBr₂ were taken for experiment on depression in freezing point. It was found that one mole of X gave depression corresponding to 2 moles of particles and one mole of particles and one mole of Y gave depression due to 3 moles of particles. The structural formulae of X and Y respectively are

(a)

[Cr(H₂O)₅Cl]Br₂, [Cr(H₂O)₄Br₂]Cl. H₂O

(b)

[Cr(H₂O)₅Cl]Br₂, [Cr(H₂O)₃ClBr₂] . 2H₂O

(c)

[Cr(H₂O)₅Br]BrCl, [Cr(H₂O)₄ClBr]Br. H₂O

(d)

[Cr(H₂O)₅Cl]Br₂, [Cr(H₂O)₄ClBr]Br. H₂O

(e)

[Cr(H₂O)₄Br₂]Cl . H₂O, [Cr(H₂O)₅Cl]Br₂

45.

A solution containing 0.319 g of CrCl₃.6 H₂O was passed through a cation exchange resin and acid coming out of the cation exchange resin required 28.5 ml of 0.125 M NaOH. Determine correct formula of the complex [Mol.wt, of the complex = 266.5]

(a)

[Cr(H₂O)₆]Cl₃

(b)

[Cr(H₂O)₅Cl]H₂O.Cl₂

(c)

[Cr(H₂O)₄Cl₂]Cl.2 H₂O

(d)

[Cr(H₂O)₃Cl₃].3H₂O

46.

Which of the following is not considered as an organometallic compound?

(a)

cis-platin

(b)

ferrocene

(c)

Zeise's salt

(d)

Grignard reagent

47.

The oxidation state of nickel in [Ni(CO)₄] is

(a)

(b)

(c)

(d)

48.

The correct structure of Fe(CO)₅ is

(a)

octahedral

(b)

terahedral

(c)

square pyramidal

(d)

trigonal bipyramidal

49.

Which of the following statement is correct? (CFSE= Crystal Field Splitting Energy)

(a)

Lower CFSE favours formation of low spin complex

(b)

Higher CFSE favours formation of high spin complex

(c)

A particular metal ion in a particular oxidation state can form either diamagnetic complexes only or paramagnetic complexes only.

(d)

t_2g orbitals are three fold degenerate while e_g orbitals are two fold degenerate

50.

Which of the following factor may be regarded as the main cause of lanthanide contraction ?

(a)

Poor shielding of one of the 4f - electrons by another in the subshell

(b)

Effective shielding of one of the 4f - electrons by another in the subshell

(c)

Poorer shielding of 5d electrons by 4f electrons

(d)

Greater shielding of 5d electrons by 4f electrons.

51.

KMnO₄, oxidation number of Mn is

(a)

+ 2

(b)

+ 4

(c)

+ 6

(d)

+ 7

52.

Permanent magnets are generally made of alloys of

(a)

(b)

(c)

(d)

Any one of these

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Answers Key:

Generic 2

6 x 2 = 12

(i) They are usually hard.
(ii) They have often high melting points.

(i) As CO is a good σ-sigma donor and a good \(\pi \) -acceptor ligand, there exists a back bonding in CO complexes in which CO accepts an appreciable amount of electron density from the filled d-orbitals of metal atom into their
empty \(\pi \) or \(\pi \)^* orbitals. Whereas NH3 can form only \(\pi \)-bonds and no σ-bonds with metals, therefore CO is a better complexing reagent than NH₃.
(ii) In Ni(CO)₄ Ni has an oxidation state equal to zero and involves sp³-hybridisation hence possesses a tetrahedral shape. While in [Ni(CN)₄]^2- the oxidation state of Ni is +2 and it involves dsp²-hybridisation, hence, possesses a square planar structure.

[Co(NH₃)₅Cl] SO₄ and [Co(NH₃)₅(SO₄)]Cl is an example of ionisation isomerism

La(OH)3 is more basic than Lu(OH)3 As the size of the lanthanoid ions decreases from La3+ to Lu3+, the covalent character of the hydroxides increases (Fajan's rules). Hence, the basic strength decreases from La(OH)3 to Lu(OH)3.

The extent of H-bonding and hence solubility in water decreases as the steric hindrance due to the size of alkyl/aryl groups increases. Thus, solubility increases in the order:
C₆H₅NH₂<(C₂H₅)₂NH2H₅NH₂

It is due tp presence of lone pair of electronson nitrogen which they can donate and act as nucleophiles.

Generic 3

6 x 3 = 18

\(\begin{equation} \begin{aligned} &\text { (i) } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl} \stackrel{\mathrm{KCN}}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CN} \stackrel{\mathrm{H}_{2} / \mathrm{Ni}}{\longrightarrow}\\ &\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2} \stackrel{\mathrm{CH}_{3} \mathrm{COCl} / \text { Base }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NHCOCH}_{3} \end{aligned} \end{equation}\)(A)
B C
\(\begin{equation} \text { (ii) } \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}^{+} \mathrm{Cl}^{-} \stackrel{\mathrm{HBF}_{4}}{\longrightarrow} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2}^{+} \mathrm{BF}_{4}^{-} \end{equation}\)\(\xrightarrow[{\triangle }]{NaNO2/Cu}\)
\(\begin{equation} \begin{array}{c} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}_{2} \stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2} \\ \end{array} \end{equation}\)
B C

Order of stability of +2 oxidation state = Cr²⁺< Fe²⁺ < Mn²⁺

(a) (i) Transition metals show variable oxidation states, therefore, they and their compounds act as catalyst.
(ii) Oxygen can form double bond, therefore, it can form Mn₂O₇ , whereas 'F' cannot form double bonds, so, it can form MnF₄ .
(b) \(3 \mathrm{MnO}_{4}^{2-}+4 \mathrm{H}^{+} \longrightarrow \mathrm{MnO}_{2}+2 \mathrm{MnO}_{4}^{-}+2 \mathrm{H}_{2} \mathrm{O}\)

10.

(i)

IUPAC name Trioxalatocobaltate (III) ion
Structure

(ii) [Cr (CO)₆]
IUPAC name Hexacarbonylchromium
Structure

(iii) [PtCI₃(C₂H₄)]
IUPAC name: Trichloridoetheneplatinum
Structure