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51.

The co-ordination number of Cr in `[Cr(NH_(3))_(3)(H_(2)O)_(3)]Cl_(3)` isA. 3B. 4C. 6D. 2

Answer» Correct Answer - C
C.N.of Cr in the give complex is 6.
52.

In the coordination compound, `K_4[Ni(CN)_4]` oxidation state of nickel isA. `-1`B. 0C. `+1`D. `+2`

Answer» Correct Answer - B
`K_(3)[Ni(CN)_(4)]` of Ni = `4 xx 1-4 xx 1` = 0
53.

Explain how two complexes of nickel, `[Ni(CN)_4]^(2-)` and `Ni(CO)_4` have different structures but do not differ in magnetic behaviour.

Answer» The complex `[Ni(CN)_(4)]^(2-)` and `[Ni(CO)_(4)]` is square planar while `[Ni(CO)_(4)]` is tetrahedral in nature. The differnence in nature. The difference arises because of the oxidation states of the metal atom/ion in the two complexes. But since all the electron orbitals of hte central metal atom/ion in these complexes are paired, both are therefore, diamagnetic in nature.
54.

The IUPAC name of the `K_(2)[Ni(CN)_(4)]` is :A. potassium tetracyanonickelate (II)B. potassium tetracynonickelate (III)C. potassium tetracyanotonickelate (II)D. Potassium tetracyanonickel (III)

Answer» Correct Answer - A
a) it is the correct answer.
55.

(a) Write the IUPC names of the following co-ordination compounds (i) `[Ce(NH_(3))_(4) (H_(2)O)_(2)]Cl_(3)` (ii) `[PtCl_(2)(NH_(3))_(4)] [PtCl_(4)]` (b) State the hybridisation and magnetic property of `[Fe(CN)_(6)]^(3-)` ion according to the valence bond theory .

Answer» (a) (i) tetraamminediaquachromium (III) chloride (ii) tetramminedichloridoplatinum (IV) tetrachloridoplatinate (II)
(b) `d^(2)sp^(3)` hybridisation, inner orbital complex and weakly paramagnetic . For details , consult section 10.
56.

The oxidation state of nickel in `K_(4)Ni(CN)_(4)` is:

Answer» Correct Answer - A
`K_(4)[Ni(CN)_(4)]`
`x+4(-1)=-4`
`x=-4+4`= zero
57.

`[NiCl_(4)]^(2-)` is paramagnetic while `[Ni(CO)_(4)]` is diamagnetic though both are tetrahedral. Why?

Answer» The `Cl^(-)` is a weak field ligand and cannot cause the electron pairing . On the other hand , CO is a strong field ligand and can cause the electron pairing .
That is why , `(NiCl_(4))^(2-)` is paramagnetic while `[Ni(CO)_(4)]` is diamagnetic nature . For details , consult section 10 .
58.

`Ag^(+)+hArr|Ag(NH_(3))_(2)|^(+), k_(1) = 6.8 xx 10^(-3)` `[Ag(NH_(3))]^(+) + NH_(3)hArr |Ag(NH_(3))_(2)|, k_(2) = 1.6xx10^(-3)` Then the formation constant or `|Ag(NH_(3))_(2)|^(+)` isA. `1.08 xx 10^(-7)`B. `1.08 xx 10^(-5)`C. `1.08 xx 10^(-9)`D. none of these

Answer» Correct Answer - B
As the reaction takes place in two stages
`k = k_(1)xx k_(2) = (6.8 xx 10^(-3)) xx (1.6xx 10^(-3))`
= `10.8 xx 10^(-6) = 1.08xx 10^(-5)`
59.

From the following given co-ordination compounds find the odd one out `[Ag(NH_(3))_(2)]^(+)`, `[AgCl_(2)]^(-)`, `[Ag(CN_(2)]^(-)`, `[Ag(CN)_(4)]^(2-)`A. `[Ag(NH_(3))_(2)]^(+)`B. `[AgCl_(2)]^(-)`C. `[Ag(CN)_(2)]^(-)`D. `[Ag(CN)_(4)]^(2-)`

Answer» Correct Answer - D
Silver has shown a coordination number of four
60.

Calculate the oxidation state of metal ion in: i) `[Ag(CN)_(2)]^(-)` ii) `[Ni(CO)_(4)]` iii) `[Fe(CN)_(6)]^(3-)`

Answer» i) `[Ag(CN)_(2)]^(-)] : x+2(-)=-1 or x=+1`
ii) `[Ag(CN)_(2)]^(-): x+4(0)=0` or x=0
iii) `[Fe(CN)_(6)]^(3-)` : `x+6(-1)=-3` or `x=+3`.
61.

In the silver plating of copper, `K[Ag(CN)_(2)]` is used instead of `AgNO_(3)` . The reason isA. A thin layer of Ag is formed on CuB. More voltage is requiredC. `Ag^(+)` ions are completely removed form solutionD. Less availability of `Ag^(+)` ions, as Cu cannot displace Ag from `[Ag(CN)_(2)]^(-)` ion.

Answer» Correct Answer - D
In the silver plating of copper, `K[Ag(CN)_(2)]` is used instead of `AgNO_(3)`. This is because if `AgNO_(3)` is used , Cu will displace `Ag^(+)` from `AgNO_(3)` . The deposit so obtained is black , soft , flaky and non-adhering . To get a good shining deposit `[Ag(CN)_(2)]^(-)` ions are used . As it is a stable complex, the concentration of `Ag^(+)` ions is very small in the solution. As such no displacent of `Ag^(+)` ions with Cu is possible.
62.

`Ag^(+) + NH_(3) ltimplies [Ag(NH_(3))]^(+), k_(1)=6.8 xx 10^(-5)` `[Ag(NH_(3))]^(+) + NH_(3) ltimplies [Ag(NH_(3))_(2)]^(+)`, `k_(2) = 1.6xx10^(-3)` The formation constant of `[Ag(NH_(3))_(2)]^(+)` is :A. `1.08 xx 10^(-7)`B. `1.08 xx 10^(-5)`C. `1.08 xx 10^(-9)`D. none of these

Answer» Correct Answer - a
k = `k_1 xx K_2`
= `(6.8 xx 10^(-5)) xx (1.6 xx 10^(-3))`
= `1.08 xx 10^(-7)`.
63.

The magnetic moment of salt containing `Zn^(2+)` ion is :

Answer» Correct Answer - a
a) it is the correct answer.
64.

Why do compounds having similar geometry have different magnetic moment ?

Answer» This is because of the nature of the ligands present in the complex. If the crystal field stabilising energy (CFSE) i.e. `Delta_(0)` for the complex is high, the complex will have less number of unpaired electrons and less value of magnetic moment. In case `Delta_(0)` is low, the complex will have more number of unpaired electrons and high value of magnetic moment. For exmaple, both `[CoF_(6)]^(3-)` and `[Co(NH_(3))_(6)]^(3+)` are octahedral complexes. Whereas former is paramagnetic, the latter is of diamagnetic nature. This is due to the reason the `F^(-)` ion has lesser `Delta_(0)` value as compared to `NH_(3)` molecule.
65.

a) State the hybridisation & magnetic behaviour of `[Cr(CO)_(6)]` b) What are the various factors affecting crystal field splitting energy? c) Which of the two is more stable and why? `K_(4)[Fe(CN)_(6)]` or `[K_(3)[Fe(CN)_(6)]`

Answer» a) Hybridisation state of Cr in the complex is `d^(2)sp^(3)`. It is octahedral and is diamagnetic.
c)`K_(3)[Fe(CN)_(6)]` is more stable than `K_(4)[Fe(CN)_(6)]` because Fe is in `+3` oxidation state while in the othe complex, it is in `+2` oxidation state. Moreover, the size of `Fe^(3+)` ion is smaller than that of `Fe^(2+)` ion. As a result, the ligands are held more closely by the `Fe^(3+)` ion than by `Fe^(2+)` ion.
66.

Arrange following complex ions in increasing order of crystal field splitting energy `(Delta_(0))`, `Cr(Cl)_(6)]^(3-)`, `[Cr(CN)_(3)]^(3-)`, `[Cr(NH_(3))_(6)]^(3+)`

Answer» The order of increasing `Delta_(0)` value for the complex ions is:
`[CrCl_(6)]^(3-) lt [Cr(NH_(3))_(6)]^(3+) lt [Cr(CN)_(4)]^(3-)`
This is because of increasing order of the `Delta_(0)` valuesof the ligands in the spectrochemical series.
67.

An arrangement of various ligands in decreasing order of crystal field splitting tendency is know asA. Nephelauxetic seriesB. Spectrochemical seriesC. Electrochemical seriesD. Macrocylic effect.

Answer» See Note Worthy Points .
68.

Cobalt is present inA. Vitamin `B_(1)`B. Vitamin `B_(2)`C. Vitamin `B_(6)`D. Vitamin `B_(12)`

Answer» The central metal atom in vitamin `B_(12)` is cobalt (Co).
69.

Phthalocyanin blue, the blue pigment present in feathers of a peacock is a complex compound ofA. CopperB. CobaltC. NickelD. None of these.

Answer» Phthalocyanin is a complex compound of copper.
70.

Arrange the following complexes in the increasing order of conductivity of their solution `[Co(NH_(3))_(3)Cl_(3)], [Co(NH_(3))_(4)Cl_(2)]Cl, [Co(NH_(3))_(6)]Cl_(3), [Cr(NH_(3))_(5)Cl] Cl_(2)`

Answer» All the complexes are of octahedral nature. The increasing order of conductivity is related to the number of ions that are available in solution. The correct order is:
`[Co(NH_(3))_(3)Cl_(3)] lt [Cr(NH_(3))_(4)Cl_(2)]Cl lt Co(NH_(3))_(5)Cl_(2) lt [Co(NH_(3))_(6)]Cl_(3)`
71.

The green pigment present in plants , chlorophyll contains the metalA. AlB. FeC. MgD. Ca

Answer» Correct Answer - C
The green pigment present in plants contains magnesium.
72.

When ammonia is added to green aqueous solution of nickel (II) sulphate, the colour of the solution changes to the violet. This is caused byA. nickel ion undergoing a change in oxidation stateB. ammonia molecules replacing water molecules surrounding nickelC. change in co-ordination number of nickelD. change in pH value of the solution.

Answer» Correct Answer - B
The colour change is due to replacement of water molecules surrounding Ni by the ammonia molecules.
73.

The expected freezing point of `0.0100` m `[Co(NH_(3))_(5)Cl]Cl_(2)` isA. `+ 0.0279^(@)`CB. `-0.0279^(@)` CC. `0.0186^(@)` CD. `0.0558^(@)` C

Answer» See Comprehensive Review.
74.

Berlin green isA. `[Pt(NH_(3))_(4)][PtCl_(4)]`B. `{:(III),(Fe[Fe(CN)_(6)]):}`C. `Cr_(2)O_(3)`D. `{:(III),(K_(3)[Co(NO_(2))_(6)]):}`

Answer» See Comprehensive Review.
75.

Which of the following complexes exhibits the highest paramagnetic behaviour? where gly=glycine, en=ethylenediamine and bipy =bipyridyl (At. no. `Ti=22, V=23, Fe=26, Co=27`)A. `|V(gly)_(2)(OH)_(2)(NH_(3))_(2)|^(2+)`B. `|Fe(en)(bpy)(NH_(3))_(2)|^(3+)`C. `|Co(OX)_(2)(OH)_(2)|^(2-)`D. `|Ti(NH_(3))_(6)|^(3+)`

Answer» Correct Answer - C
Oxidation state of V in (A) `x + 2 (-1) + 2(-1) +` = `+1` or x = `+5`
Valence shell configuration `3d^(0)`
Number of unpaired electron 1.
Oxidatios state of Fe in (B) `x + 0 + 0 + 0 = +2` or = `+2`
Valence shell configuration = `3d^(6)` (i.e. 4 unpaired electrons)
Oxidation state of Co in (C) `x+ 2 (-2) + 2(-1) = -2 or x = +4`
Valence shell configuration = `3d^(5)` (i.e. 5 unpaired electron)
Oxidation state of Ti in (D)
`x + 6(0) = + 3 or x = +3`
Valence shell configuration = `3d^(1)` (i.e. 1 unpaired electron).
Thus complex of cobalt has maximum unpaired electrons (viz 5 ) and hence has highest paramagnetism.
76.

AgCl dissolves in `NH_(4)OH` due to the formation ofA. `[Ag(NH_(4))_(2)]Cl`B. `[Ag(NH_(4))_(3)]Cl`C. `[Ag(NH_(3))_(2)]Cl`D. `[Ag(NH_(3))_(2)]OH.`

Answer» Correct Answer - C
`underset("White ppt.")(AgCl(s)) + 2NH_(4)OH (aq)rarrunderset("Soluble complex")([Ag(NH_(3))_(2)]Cl (aq)) + 2H_(2)O(l)`
77.

The effective atomic number of Fe in `Fe(CO)_(5)` isA. 26B. 34C. 36D. 54

Answer» Correct Answer - C
`EAN = Z-O.N+2xxC.N.`
=`26-O+2xx5=36`
78.

Number of electrons gained by Pd (for coordination ) in `[PdCl_(4)]^(2-)` isA. 4B. 8C. 10D. zero

Answer» Correct Answer - B
No. of electrons gained
= `2xx` No. of monodentat ligands
= `2 xx 4 = 8`
79.

The effective atomic number of Cr(at. No. 24) in `[Cr(NH_(3))_(6)]Cl_(3)` isA. 35B. 27C. 33D. 36

Answer» Correct Answer - C
Effective atomic number = Elecrtrons on `Cr^(3+) +` Electrons from 6 `NH_(3)` ligands .
`=21 +6 xx 2 = 21 + 12 = 33`.
80.

Which of the following facts about the complex `[Cr(NH_(3))_(6)]Cl_(3)` is wrong ?A. The complex involves `d^(2)sp^(3)` hybrdisation and is octahedral in shapeB. The complex is paramagnetic in natureC. The complex gives a while precipitate with `` solution .D. The complex gives a white precipitate with `AgNO_(3)` solution.

Answer» Correct Answer - C
It is an inner orbital complex since the state of hybridisation is `d^(2)sp^(3)`
81.

The oxidation states of Cr in `[Cr(H_(2)O)_(6)]Cl_(3). [Cr(C_(6)H_(6))_(2)]` and `K_(2)[Cr(CN)_(2)(O)_(2)(O_(2))(NH_(3))]` respectively areA. `+3, +2` and `+4`B. `+3, 0` and `+6`C. `+3, 0 ` and `+4`D. `+3, +4` and `+6`

Answer» Correct Answer - B
`[Cr(H_(2)O)_(6)]Cl_(3)`
`rArr x+0xx6-1xx3=0`
or `x=+3`
`[Cr(C_(6)H_(6))_(2)]`
`rArr x+2xx0=0`
or `x=0`
`[Cr(CN)_(2)(O)_(2)NH_(3)]^(2-)`
`x+2(-1)+2(-2)+2(-1)+0=-2`
`x-2-4-2=-2 or x=+6`
82.

AgCl reacts with aqueous solution of sodium thiosulphate and potassium cyanide solutions to give :A. `Na[Ag(S_(2)O_(3))_(2)]` and `K[Ag(CN)_(2)]`B. `Na[Ag(S_(2)O_(3))_(2)]` and `K_(3)[Ag(CN)_(2)]`C. `Na_(3)[Ag(S_(2)O_(3))_(2)]` and `K[Ag(CN)_(2)]`D. `Na_(3)[Ag(S_(2)O_(3))_(2)]` and `K[Ag(CN)_(2)]`

Answer» Correct Answer - C
c) it is the correct answer.
83.

Which of the following complexes has lowest molar conductance ?A. `CoCl_(3).3NH_(3)`B. `CoCl_(3).4NH_(3)`C. `CoCl_(3).5NH_(3)`D. `CoCl_(3).6NH_(3)`

Answer» Correct Answer - A
The complex [`CoCl_(3)NH_(3)`] has the lowest molar conductance since it furnishes no ion in the aqueous solution.
84.

Which of the following will exhibit maximum ionic conductivity?A. `K_(4)[Fe(CN)_(6)]`B. `[Co(NH_(3))_(6)Cl_(3)`C. `[Cu(NH_(3))_(4)]Cl_(2)`D. `[Ni(CO)_(4)]`

Answer» Correct Answer - A
`K_(4)[Fe(CH)_(6)](aq)hArr4K^(+)(aq)^(+)+[Fe(CN)]^(4-)(aq)`
It gives five ions in solution .
`[Co(NH_(3))_(6)]Cl_(3)(aq)hArr[Co(NH_(3))_(6)](aq)+3Cl^(-)(aq)`
It gives four ions in solution .
`[Cu(NH_(3))_(4)]Cl_(2)(aq)hArr[Cu(NH_(3))_(4)]^(2+)(aq)+2Cl^(-)(aq)`
It gives three ions in solution.
`[Ni(CO)_(4)]` is not an ionic compound .
`K_(4)[Fe(CN)_(6)` gives maximum ions in solution and as such shows maximum ionic conductivity .
85.

The oxidation state of `Cr` in `[Cr(NH_(3))_(4)Cl_(2)]^(+)` is:A. `+2`B. `+3`C. `+4`D. `+5`

Answer» Correct Answer - A
`[Cr(NH_3)_4Cl_2]^(+)`
x + 4(0) + 2(-1) + +1
x = +1 + 2 = +3
86.

The oxidation state of `Cr` in `[Cr(NH_(3))_(4)Cl_(2)]^(+)` is:A. `+3`B. `+2`C. `+1`D. 0

Answer» Correct Answer - A
`[Cr(NH_(3))_(4)Cl_(2)]^(+)`
Let O.S. of Cr = x
`x + 4 xx 0 + 2 xx (-1) = +1`
`x -2 = 1`
x = `+3`
87.

EAN of iron in `K_(4)[Fe(CN)_(6)]` isA. 1B. 2C. 3D. 4

Answer» Correct Answer - B
Primary valency of iron in `K_(4)[Fe(CN)_(6)]` is 2 . This complex contains `Fe^(2+)` in the coordination sphere .
88.

The geometry of the compound `[Pt(NH_(3))_(2)Cl_(2)]` isA. Square planarB. PyramidalC. TetrahedralD. octahedral

Answer» Correct Answer - A
O.S.of Pt (Z = 78) in the complex is `+2(Pt^(2+))Pt^(2+) : [Xe]^(54)4f^(14)5d^(8)`
The eight electrons in 5d-subshell pair up in four d-orbitals followed by `dsp^(2)`-hybridisation. The shape of the complex is square planar.
89.

Which of the following is paramagnetic?A. `[Co(NH_(3))_(6)]^(3+)`B. `[Ni(CO)_(4)]`C. `[Ni(NH_(3))_(4)]^(2+)`D. `[Ni(CN)_(4)]^(2-)`

Answer» Correct Answer - C
`Ni(Z = 28) : [Ar]^(18)4s^(2)3d^(8)`
`Ni^(2+) : [Ar]^(18)3d^(8)`
`[Ni(NH_(3))_(4)]^(2+)` : `Ni^(2+)` undergoes `sp^(3)`-hybridisation the resulting ion is paramagnetic due to the presence two unpaired electrons .
`Ni(CO)_(4)` : Two 4s-electrons in Ni pair up with 3d-electrons followed by `sp^(3)`-hybridisation . The rasulting complex has no unpaired electron and is diamagnetic.
`[Ni(CN)_(4)]^(2-)` : `CN^(-)` being a strong ligand , pairs up the two unpairad electrons in d-subshell of `Ni^(2+)` . This is followed by `dsp^(2)`-hybridisation . The complex ion has on unpaired electron and is diamagnetic.
`[Co(NH_(3))_(6)]^(3+)` : `Co^(3+)` with `3d^(6)`-configuration undergoes `d^(2)sp^(3)`-hybridisation , after pairing up of all the six d-electrons in three d-orbitals . As the ion has no unpaired electron , it is diamagnetic.
90.

The correct statement with respect to the complexes `Ni(CO)_(4) and |Ni(CN)_(4)|^(2-)` isA. nickel is in the same oxidation state in bothB. both have tetrahedral geometryC. both have square planar geometryD. have tetrahedral and square planar geometry respectively.

Answer» `Ni(CO)_(4)rarrsp^(3)"hybridisation"rarr"tatrahedral"`
`|Ni(CN)_(4)|^(2-)rarrdsp^(2)"hybridisation"rarr "square planar"`
91.

IUPAC name of `Na[CoCl(NO_(2))_(5)]` isA. chloronitrodis (ethylendiamine) cobaltic (III) chlorideB. chloronitrobis(ethylendiamine) cobalt (II) chlorideC. chlorodis (ethylediamine)nitrocobalt(III)chorideD. bis(ethylenediamine)chloronitrocobalt(III) chloride.

Answer» Correct Answer - C
See Comprehensive Review. (IUPAC system of nomenclature).
92.

Which of the following cations does not form complex with ammonia?A. `Al^(3+)`B. `Ag^(+)`C. `Cu^(2+)`D. `Cd^(2+)`

Answer» Correct Answer - A
`Al^(3+)` does not form complexes with `NH_(3)` .
93.

Which of the following pairs represents linkage isomers ?A. `[Cu(NH_(3))_(4)][PtCl_(4)]` and `[Co(en)_(3)]^(2+)`B. `[Pd(PPh_(3))_(2)(NCS)_(2)]` and `[Pd(PPh_(3))_(2)(SCN)_(2)]`C. `[Co(NH_(3))_(5)(NO_(3))]SO_(4)` and `[Co(NH_(3))_(5)(SO_(4))]NO_(3)`D. `[PtCl_(2)(NH_(3))_(4)]Br_(2)` and `[PtBr_(2)(NH_(3))_(4)]Cl_(2)`

Answer» Correct Answer - B
The pair exhibits linkage isomerism.
94.

The oxidation number of metal atom is zero inA. `[Ni(CO)_(4)]`B. `[Fe_(2)(CO)_(5)]`C. `Na[Co(CO)_(4)]`D. Cu

Answer» Correct Answer - a,b,c,d
(a,b,c) are correct.
95.

The geometry and magnetic behaviour of the complex `[Ni(CO)_4]` areA. square planar and geometry and diamagneticB. tetrahedral geometry and diamagneticC. tetrahedral geometry and paramagneticD. tetrahedral geometry and paramagnetic.

Answer» Correct Answer - B
`[Ni(CO)_4]` is tetrahedral and diamagnetic in nature. For details , consult section 10 .
96.

`K_(4)[Fe(CN)_(6)]` is used for detection ofA. `Fe^(+)` ionsB. `Fe^(3+)` ionsC. `Zn^(2+)` ionsD. `Cu^(2+)` ions.

Answer» Correct Answer - B::C::D
`K_(4)[Fe(CN)_(6)]` or potassium ferrocyanide gives dark bluk colouration with `Fe^(3+)` ions , with `Cu^(2+)` ions `Zn^(2+)` ions and reddish brown ppt. with `Cu^(2+)` ions.
97.

The oxidation state of Fe in brown complex `[Fe(H_(2)O)_(5)NO]SO_(4)` isA. `+1`B. `+2`C. `+3`D. `+4`

Answer» Correct Answer - A
Oxidation state of Fe in `[Fe(H_(2)O)_(5)NO]SO_(4) is +1` as water `(H_(2)O)` is a neutral ligands with `NO^(+) -a` postivie ligand NO is an odd electron molecule . It gives its one unpaired electron to `Fe^(2+)`
98.

Which of the following statements are correct regarding `[Fe(H_(2)O)_(5)NO]SO_(4)` ?A. it gives a brown ring test for nitratesB. oxidation state of Fe is +2C. charge on NO is +1D. C.N . Fe is 6.

Answer» Correct Answer - a,b,d
(a,b,d) are correct .
99.

Which of the following statements about `[Fe(H_(2)O)_(5)NO]^(2-)` are correct ?A. O.S. of Fe is `+1`B. C.N. of Fe is 6C. Charge on NO is `+1`D. O.S. of Fe is `+2`

Answer» Correct Answer - A::B::C
In `[Fe(H_(2)O)_(5)NO]^(2+)`, O.S. of Fe is `+1` . There is one `NO^(+)` and five `H_(2)O` ligand . Coordination number of Fe is six in this complex as `H_(2)O` and `NO^(+)` are both monodentate.
100.

violet coloured complex obtained in the detectiomn of sulphur is :A. `Na_(2)[Fe(NO)(CN)_(5)]`B. `Na_(3)[Fe(ONSNa)(CN)_(5)]`C. `Na_(4)[Fe(CN)_(5)NOS]`D. Both (b) and (c)

Answer» Correct Answer - D
Both (b) and (c ) are the same .