InterviewSolution
Saved Bookmarks
InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Which of the following statements is correct?A. The lesser number of oxidation states in 3d-series in the begin inning of the series is due to the presence of too few electrons to loose or shareB. The lesser number of oxidation states in 3d-series towards the end of the series is due to the presence of too many electrons and thus fewer orbitals to share electrons with the ligands.C. A and B bothD. None is correct |
|
Answer» Correct Answer - C The lesser number of oxidation states in the beginning of series can be due to the presence of smaller number of electrons to lose or share (Sc,Ti). On the other hand, at the extreme right hadn side and (Cu,Zn), lesser number of oxidation state is due to large number of d electrons so that only a fewer orbitals are available in which the electron can share with other for higher valence. |
|
| 52. |
Which one of the following ionic species will impart colour to an aqueous solution ?A. `Ti^(4+)`B. `Cu^(+)`C. `Zn^(2+)`D. `Cr^(3+)` |
|
Answer» Correct Answer - D In `Ti^(4+),Cu^(+) and Zn^(2+)`, all have electrons paired so all are diamagnetic . `Cr^(3+)` with electron configuration `[Ar]^(18)3d^(3)` has three unpaired electrons. So it underoes d-d transition of electrons in presence of ligands according to CFT and thus it is coloured. |
|
| 53. |
`CuSO_(4).5H_(2)O` is blue in colour becauseA. It contains water of crystallizationB. `SO_(4)^(2-)` ions absorb red lightC. `Cu^(2+)` ions absorb red lightD. `Cu^(2+)` ions absorb all colours except red from the white light. |
|
Answer» Correct Answer - C `Cu^(+)`ion `(3d^9)` absorbs red light from the visible region, for the promotion of 3d electrons, the ions reflect blue light and appear blue. |
|
| 54. |
In how many of the following reactions, colored precipitate is obtained? (a). `CuSO_(4)+NaoH("excess")to`, (b) `CuCl_(2)+NH_(3)("excess")to` ltBrgt (c) `ZnSO_(4)+NaOH("excess")to` (d) `ZnSO_(4)+NH_(3)("excess")to` , (e) `FeSO_(4)+NaOH("excess")underset(air)overset("in")to` , (f) `FeCl_(3)+NaoH("Excess")to` (g) `CuSO_(4)+Kl("excess")to`, (h) `ZnSO_(4)+NaHCO_(3)to` (i) `CuCl_(2)+NaNO_(3)to` |
|
Answer» Correct Answer - 3 (a) `Cu(OH)_(2)darr(blue)` (b) `[Cu(NH_(3))_(4)]^(2+)(aq.)` (c). `Na_(2)[Zn(OH)_(4)](aq.)` (d). `[Zn(NH_(3))_(4)]^(2+)(aq.)` (e) `Fe(OH)_(2)darr("greenish")` (f) `Fe(OH)_(3)darr("reddish brown")` (g) Cul (white) (h) `ZnCO_(3)darr ("white")` (i) `Cu(NO_(3))_(2)darr(aq.)` |
|
| 55. |
The image on an exposed and developed photographic film is due toA. `AgBr`B. `[Ag(C_(2)O_(3))_(2)]^(3+)`C. `Ag`D. `Ag_(2)O`. |
|
Answer» Correct Answer - C Quinol developer (a reducing agent) reduces AgBr to Ag. `2AgBr^(+)(s)+2OH^(-)(aq)+C_(6)H_(5)(OH)_(2)(aq)to2Ag(s)+2H_(2)O+C_(6)H_(4)O_(2)(aq)+2Br^(-)(aq)` Where `AgBr^(+)` represents a molecules of AgBr exposed to light. |
|
| 56. |
Which of the following statement wrong?A. An acidified solution of `K_(2)Cr_(2)O_(7)` liberates iodine from iodides.B. In acidic solution dichromate ions are converted to chromate ions.C. Ammonium dichromate on heating undergo exothermic decomposition to give `Cr_(2)O_(3)`D. Potassium dichromate is u sed as a titrant for `Fe^(2+)`. |
|
Answer» Correct Answer - B (1) `Cr_(2)O_(7)^(2-)+14H^(+)+6I^(-)to2Cr^(3+)+3I_(2)+7H_(2)O` 2. In acidic solution, actually chromate is converted to dichromate to dichromate. `2CrO_(4)^(2-)+2H^(+)toCr_(2)O_(7)^(2-)+H_(2)O` 3. `(NH_(4))_(2)Cr_(2)O_(7)overset(Delta)toN_(2)+4H_(2)O+Cr_(2)O_(3)`. 4. `6Fe^(2+)+Cr_(2)O_(7)^(2-)+14H^(+)to6Fe^(3+)+2Cr^(3+)+7H_(2)O` |
|
| 57. |
What happens when: (a). Green vitriol is strongly heated. (b). Malachite is made to react with dilute `H_(2)SO_(4)` (c). Copper sulphate is exposed to air for longer period. ltBrgt (d). Lunar caustic is made to react with sodium hydroxide and then product is dried. (e). Silver nitrate reacts with excess iodine. (f). Potassium dichromate reacts with cold and concentrated `H_(2)SO_(4)`. |
|
Answer» (a). `FeSO_(4).7H_(2)Ounderset(H_(2)O)overset(300^(@)C)toFeSO_(4)underset("tempt")overset(high)toFe_(2)O_(3)+SO_(2)+SO_(3)` (b) `CuCO_(3).Cu(OH)_(2)+2H_(2)SO_(4)to2CuSO_(4)+3H_(2)O+CO_(2)uarr` (c) `CuSO_(4).5H_(2)Ounderset("ettloresces")overset(air)toCuSO_(4).3H_(2)O` (d) `2AgNO_(3)+2NaOHtoAg_(2)Odarr("black")+2NaNO_(3)+H_(2)O` ltbr (e). `5AgNO_(3)+3I_(2)("excess")+H_(2)OtoHIO_(3)+5AgIdarr("yellow")+5HNO_(3)` (f) `K_(2)Cr_(2)O_(7)+2H_(2)SO_(4)(conc.&" "cold)to2CrO_(3)(red)+2KHSO_(4)+H_(2)O` |
|
| 58. |
Write balaned chemical equations for: (i) Mixture of `K_(2)Cr_(2)O_(7)` and `NaCl` is heated with concentrated `H_(2)SO_(4)`. (ii) Potassium permanganate is added to a hot solution of manganous sulphate. (iii). Potassium dischromate and concentrated HCl are heated together. |
|
Answer» (i) `K_(2)Cr_(2)O_(7)+4NaCl+6H_(2)SO_(4)tounderset("Orange")(2CrO_(2)Cl_(2))uarr+4NaHSO_(4)+2KHSO_(4)+3H_(2)O` (ii) `2KMnO_(4)+3MnSO_(4)+2H_(2)Oto5MnO_(2)+K_(2)SO_(4)+2H_(2)SO_(4)` (iii) `K_(2)Cr_(2)O_(7)+14HCl underset(Delta)to2KCl+2CrCl_(3)+7H_(2)O+3Cl_(2)`. |
|
| 59. |
Select the incorrect statement(s):A. In `K_(2)MnO_(4)` and `CrO_(2)Cl_(2)` the central transition metals/ions have same oxidation state.B. Both sodium and potassium dichromate can be used as primary standard in volumetric estimations.C. Potassium dichromate on strong heating evolves oxygen gas and forms green powder.D. Potassium dichromate on strong heating evolves oxygen gas forms green powder. |
|
Answer» Correct Answer - B::D (A) In both compounds central metals have +6 oxidaiton states. `MnO_(4)^(2-),x+4(-2)=-2,` So, `x=6` , `CrO_(2)Cl_(2)," "x+2(-2)+2(-1)=0,` so `x=6` (B) Sodium dichromate is `Na_(2)Cr_(2)O_(7).2H_(2)O`, so it can not be weighed correctly for the preparation of standard solutions. (C) `2K_(2)Cr_(2)O_(7)overset(Delta)to2K_(2)CrO_(4)+Cr_(2)O_(3)("green")+3//2O_(2)`. (D) `4KMnO_(4)+4KOHoverset(Delta)to4K_(2)MnO_(4)("green")+2H_(2)O+O_(2)`. |
|
| 60. |
Copper metal reduces `Fe^(2+)` in an acid medium. |
|
Answer» Correct Answer - F |
|
| 61. |
When `I^(Theta)` is oxidised by `MnO_(4)^(Theta)` in an alkaine medium, `I^(Theta)` converts intoA. `IO_(3)^(-)`B. `I_(2)`C. `IO_(4)^(-)`D. `IO^(-)` |
|
Answer» Correct Answer - A |
|
| 62. |
`CrO_3` dissolves in aqueous NaOH to giveA. `Cr_(2)O_(7)^(2-)`B. `CrO_(4)^(2-)`C. `Cr(OH)_(3)^(2-)`D. `Cr(OH)_(2)` |
|
Answer» Correct Answer - 2 `NaOH+CrO_(3)rarrNa_(2)CrO_(4)+H_(2)O` |
|
| 63. |
Why do transition elements show variable oxidation state? |
| Answer» The energies `(n-1)d` orbitals and ns orbitals are very close. Hence, electrons from both can participate in bonding. | |
| 64. |
What is the most common oxidation state of first transtion series.? |
| Answer» Correct Answer - `+2` | |
| 65. |
Among the following, identify the species with an atom in `+6` oxidation state.A. `MnO_(4)^(-)`B. `Cr(CN)_(6)^(3-)`C. `NiF_(6)^(2-)`D. `CrO_(2)Cl_(2)` |
|
Answer» Correct Answer - D |
|
| 66. |
How many of given statements are true for lanthanums? 1. The common oxidation state of all lanthanides is +3. 2. All lantanides belongs to group III of modern periodic table. 3. All lanthanides belongs to seventh period of periodic table 4. The radius for all lanthanides cations `(M^(+3))` decrease from `Ce^(+3)` to `Lu^(+3)`. 5. The basic character of hydroxide increases on moving from `Ce(OH)_(3)` to `Lu(OH)_(3)` 6. All lanthanides are metals. 7. The reducing power of lanthanides decreases from Ce to Lu. 8. Lanthanides reacts with cold water to liberate `H_(2)`. |
|
Answer» Correct Answer - 6 1. All lanthanides exhibits +3 O.N. but few also exhibit +2 and +4 O.N. (2) Correct (3). Incorrect as all belongs to `6^(th)` period. (4) True due to lanthanide contraction. (5). Incorrect as basicing decreases from `Ce(OH)_(3)` to `Lu(OH)_(3)` becomes of fazans rule. 6. Correct 7. Correct 8. All lanthanides have -ve S.R.P. hence all releases hydrogen. |
|
| 67. |
(i) A powdered substance (A) on treatment with fusion mixture gives a green coloured compound (B). (ii) The solution of (B) in boiling water on acidification with dilute `H_(2)SO_(4)` gives a pink coloured compound `(C )`. `(iii)` The aqueous solution of (A) on treatment with NaOH and `Br_(2)-` water gives a compound (D). (iv) A solution of (D) in conc. `HNO_(3)` on treatment with lead peroxide at boiling temperature produced a compound (E) which was of the same coloure at that of (C). (v) A solution of (A) on treatment with a solution of barium chloride gave a white precipitate of compound (F) Which was insoluble in conc. `HNO_(3)` and conc. HCl. The oxidation state of central metal ions of (A), (B) and (C ) compounds are respectively `:`A. `+II,+VI and +VII`B. `+II, +VI and +VI`C. `+II,+VII and +VIII`D. `+VI,+VII and +VII` |
|
Answer» Correct Answer - A (A) In `MnSO_(4),=+II,` (B) `MnO_(4)^(2-)=+VI,` (C) `MnO_(4)^(-)=+VII` |
|
| 68. |
If a non-metal is added to the interstitial sites of a metal, then the metal becomesA. softerB. less tensileC. less malleableD. more ductile. |
|
Answer» Correct Answer - C If a non-metal occupies interstitial sites of a metal, the metal becomes less malleable. This is because the non-metal atom forms covalent bonds with metal atoms and covalent bond is rigid and directional. |
|
| 69. |
On heating ammonium dichromate, the gas evolved isA. oxygenB. ammoniaC. nitrous oxideD. nitrogen |
|
Answer» Correct Answer - D |
|
| 70. |
Statement 1: The number of unpaired electrons in the following gaseous ion: `Mn^(3+),Cr^(3+),V^(3+) and Ti^(3+)` are `4,3,2` and 1 respectively Statement 2: `Cr^(3+)`is most stable in aqueous solution among these ions.A. Statement-1 is true, statement-2 is true, statement-2 is a correct explanation for statement-1B. statement-1 is true, statement-2 is true, statement-2 is NOT a correct explanation for statement-1C. Statement-1 is true, statement-2 is false.D. Statement-1 is false, statement-2 is true. |
|
Answer» Correct Answer - B `Mg^(3+)=[Ar]^(18)3d^(4),Cr^(+3)=[Ar]^(18)3d^(3),V^(3+)=[Ar]^(18)3d^(2),Ti^(3+)=[Ar]^(18)3d^(1)` `Cr^(3+)` is most stable in aqueous solution because it has half filled `t_(2g)^(3)` energy level of 3d orbitals I octahedral crystal field spliting and according to crystal field theory (CFT) it has highest value of ` CFSE` i.e., 1.2 `Delta_(O)`. |
|
| 71. |
Why are the ionisation energies of 5d elements greater than 3d elements? |
| Answer» In the 5d series, after lanthanum (Z=57) there is lanthanide contraction. As a result in each group the atomic size of 5d element is small and its nuclear charge is large. Hence, electrons from both can participate in bonding. | |
| 72. |
Transition elements are used as catalyst because `:`A. of high ionic chargeB. of variable oxidation stateC. large surface area of reactantsD. of their specific nature |
|
Answer» Correct Answer - 2 General electronic configuration of transition elements is `[` inert gas `](n-1)d^(1-10)`. Energy difference between `(n-1)d` and ns subshell is much less so electron can remove from `(n-1)d` subshells easily. Due to this variable oxidation states shown by transition elements. |
|
| 73. |
The ions from among the following which are colourless are `:` `(i)Ti^(+4)" "(ii)Cu^(+1)" "(iii)Co^(+3)" "(iv)Fe^(+2)`A. (i) and (ii) onlyB. (i),(ii) and (iii)C. (iii) and (iv)D. (ii) and (iii). |
|
Answer» Correct Answer - A (i) Valence shell electron configuration of `Ti^(4+)` is `3d^(10)4s^(0)`. As theere is no unpaired electrons for d-d transition, the solution of ions will be colourless. (ii) Valence shell electron configuration of `Cu^(+)` is `3d^(10)4s^(0)`. As all electrons are paired, there is no d-d transiton, so the solution of ions will be colourless. (iii) Valence shell electron configuraiton of `Co^(3+)` is `3d^(6)4s^(0)`. As there are 4 unpaired electrons, there is d-d transition of electron, so the solution of ions will be coloured. (iv) Valence shell electron configuration of `Fe^(2+)` is `3d^(6)4s^(0)`. As there are 4 unpaired electrons, there is d-d transition of electron, so the solution of ions will be coloured. |
|
| 74. |
The number of mole of `KMnO_(4)` that will be needed to react completely with one mole of ferrous oxalate in acidic solution is:A. `3//5`B. `2//5`C. `4//5`D. `1` |
|
Answer» Correct Answer - 1 This reaction is slow at room temperature but it rapid at `60^(@)C`. `2MnO_(4)^(-)+16H^(+)+5C_(2)O_(4)^(2-)overset(60^(@)C)rarr2Mn^(2+)+8H_(2)O+10CO_(2)` |
|
| 75. |
Assertion : `CrO_(3)` reacts with HCl to form chromyl chloride gas Reason : Chromyl chloride `(CrO_(2)Cl_(2))` has tetrahedral shape.A. Both assertion and reason are correct and reason is the correct explanation of the assertionB. Both assertion and reason are correct but reason is not the correct explanation of assertionC. Assertion is correct but reason is wrongD. Assertion is incorrect but reason is correct |
|
Answer» Correct Answer - B |
|
| 76. |
The first ionisation energies of the elements of the first transition series `(TitoCu)`A. generally increases as the atomic numbers increaseB. decrease as the atomic number increaseC. do not show any change as the addition of electrons takes place in the inner (n-1)d-orbitals.D. increase from Ti to Mn and then decrease from Mn to Cu. |
|
Answer» Correct Answer - A First ionisation energies of 3d-series (first transition sereis) increase with increase in atomic numbr due to (1) increase in nuclear charge (2) decrease in atomic size. |
|
| 77. |
A compound of iron exists as a dimer in vapour state. It is hygroscopic in nature and disolves in water giving brown acidic solution. The compound isA. `Fe_(3)O_(4)`B. `FeSO_(4)`C. `FeCl_(3)`D. `FeCl_(2)` |
|
Answer» Correct Answer - C (3) `FeCl_(3)` exist as `Fe_(2)Cl_(6)` (a dimer) in vapour state. The solution is acidic due to the formation of HCl and brown due to the formation of ` Fe(OH)_(3)`. `FeCl_(3)+3H_(2)OtoFe(OH)_(3)("brown")+3HCl` |
|
| 78. |
The formula of azurite is `:`A. `CuCO_(3).Cu(OH)_(2)`B. `2CuCO_(3). Cu(OH)_(2)`C. `CuCO_(3).2Cu(OH)_(2)`D. `CuSO_(4).Cu(OH)_(2)` |
|
Answer» Correct Answer - 2 `2CuCO_(3).Cu(OH)_(2)` |
|
| 79. |
Assertion : `KMNO_(4)` in aqueous solution is purple coloured due to charge transfer Reason : In `MnO_(4)^(-)` these is no electron present in the d-orbital of MnA. Both assertion and reason are correct and reason is the correct explanation of the assertionB. Both assertion and reason are correct but reason is not the correct explanation of assertionC. Assertion is correct but reason is wrongD. Assertion is incorrect but reason is correct |
|
Answer» Correct Answer - B |
|
| 80. |
The ratio of mass of a diamagnetic substance in a magnetic field to its actual massA. is greater than oneB. is less than oneC. is equal to oneD. cannot be predicted |
|
Answer» Correct Answer - 2 The external magnetic field induces a small magnetic moment to the diamagnetic substance . The moment in the diamagnetic substance is in opposition to the external field. Thus diamagnetic substance repel has of force, and show decrease in weight. |
|
| 81. |
Oxide of metal cation which is not amphoteric ?A. `Al^(3+)`B. `Cr^(3+)`C. `Fe^(3+)`D. `Zn^(2+)` |
|
Answer» Correct Answer - 3 `Al,Cr` and `Zn` oxide are Amphoteric in nature. `d-& f-` block Elements`_`final |
|
| 82. |
Which oxide of manganese is most acidic in nature?A. MnOB. `Mn_(2)O_(7)`C. `Mn_(2)O_(3)`D. `MnO_(2)` |
|
Answer» Correct Answer - B Transition metl oxide with highest oxidation states is most acidic in character because of the very less difference in the values of electronegativity between `Mn^(7+) and O^(2-)`, and the decreasing order of acidic character is `overset(+7)(Mn_(2))O_(7) gt overset(+4)(Mn)O_(2) gt overset(+3)(Mn_(2))O_(3) gt overset(+2)(Mn)O`. |
|
| 83. |
`VO_(2)` is an amphoteric oxide and in acidic medium it forms:A. `VO^(2+)`B. `VO_(2)^(+)`C. `V^(3+)`D. `VO_(2)^(2+)` |
|
Answer» Correct Answer - A It is an amphoteric in natrue and it reacts with alkalies as well as with acids to give `V_(4)O_(9)^(2-)` and `VO^(2+)` respectively. |
|
| 84. |
Which of the following increasing order of oxidising power is correct for the following species? `VO_(2)^(+),MnO_(4)^(-),Cr_(2)O_(7)^(2-)`A. `VO_(2^(+)) lt Cr_(2)O_(7^(2))`B. `VO_(2^(+)) lt MnO_(4) lt Cr_(2)O_(7)^(2-)`C. `Cr_(2)O_(7^(2)) lt MnO_(4)`D. `Cr_(2)O_(7^(2-)) lt MnO_(4^(-)) lt VO_(2^(+))`. |
|
Answer» Correct Answer - A This is attributed to the increasing stability of the lower species to which they are reduced. `MnO_(4)` is reduced to `Mn^(2+)` which has stable half filled valence shell electron configuration `[3d^(5)].Cr_(2)O_(7)^(2-)` is reduced to` Cr^(3+)` which has half filled `t_(2g)^(3)` energy level of 3d orbitals in octahedral crystal field spliting. `VO_(2^(+))` is reduced to `V^(3+)` which has electronic configuration `[Ar]^(18)3d^(2)4s^(0)` so the order of increasing stability of the reduced species is `Mn^(2+) gt Cr^(3+) gt V^(3+)` and, therefore, the increasing order of oxidising power is `VO_(2^(+)) lt Cr_(2)O_(7^(2-)) lt MnO_(4^(-))`. |
|
| 85. |
Match the reactions in Column I with nature of the reactions `//` type of the products in Column II. |
|
Answer» Correct Answer - A::B::C::D (A) `5AgNO_(3)(aq.)+3overset(0)(l)_(2)("excess")+3H_(2)Oto overset(+V)(HlO_(3))+5Agoverset(-1)(l)+5HNO_(3)` So it is redox and disproportionation reaction. Agl insoluble in water. (B). `3K_(2)overset(+VI)(MnO_(4))(aq)+2CO_(2)(g)to2Koverset(+VII)(MnO_(4))+Moverset(+VI)(nO_(2))+2K_(2)CO_(3)` So it is redox and disproportionation reaction. `MnO_(2)` insoluble in water. (C) `2overset(0)(C)+Na_(2)overset(+VI)(Cr_(2))O_(7)overset(Delta)toCr_(2)overset(+VII)(O_(3))+Na_(2)overset(+IV)(CO_(3))+overset(+II)(CO)uarr` So it is redox reaction, `Cr_(2)O_(3)` (green pigment) is insoluble i water. (D). `overset(+II)(C)uCl_(2)(aq)+overset(0)(Cu)(s)to overset(+I)(Cu_(2))Cl_(2)(s)`. So it is redox and comproportionation reaction. `Cu_(2)Cl_2` is insoluble in water. |
|
| 86. |
Which of the following characteristics of products obtained when green vitriol is strongly heated?A. Basic oxideB. Neutral oxideC. acidic oxideD. Reducing agent |
|
Answer» Correct Answer - A::B::C::D `FeSO_(4).7H_(2)O("Green vitriol")overset(Delta)tounderset("Basic oxide")(Fe_(2)O_(3))+underset("Neutral oxide")(H_(2)O)+undersetunderset(underset("Acidic oxide")ubrace)("Reducing agent")(SO_(2)+SO_(3))` |
|
| 87. |
Which series of reactions correctly represents chemical rections related to iron and its compounds ?A. `Fe overset("Dil." H_(2)SO_(4))(rarr) FeSO_(4) overset(H_(2)SO_(4),O_(2))(rarr) Fe_(2)(SO_(4))_(3) overset("Heat")(rarr) Fe`B. `Fe overset( O_(2)."Heat")(rarr) FeSO_(4) overset("Dil".H_(2)SO_(4))(rarr) Fe_(2)SO_(4) overset("Heat")(rarr) Fe`C. `Fe overset( Cl_(2),"Heat")(rarr) FeCl_(3) overset("Heat,air")(rarr) FeCl_(2) overset("Zn")(rarr) Fe`D. `Fe overset( O_(2),"Heat")(rarr) FeCl_(3) overset("Co,"600^(@)C)(rarr) FeO overset("CO,"700^(@)C)(rarr) Fe` |
|
Answer» Correct Answer - D |
|
| 88. |
Which of the following compounds is not yellow coloured ?A. `Zn_(2)[Fe(CN)_(6)]`B. `K_(3)[Co (NO_(2))_(6)]`C. `(NH_(4))_(3) ["As" (Mo_(3)O_(10))_(4)]`D. `BaCrO_(4)` |
|
Answer» Correct Answer - A |
|
| 89. |
The geometries of the ammonia complexes of `Ni^(2+),Pt^(2+)` and `Zn^(2+)`, respectively, areA. octahedral, square planar and tetrahedralB. square planar, octahedral and tetrahedralC. tetrahedral, square planar and octahedralD. octahedral, tetrahedral and square planar |
|
Answer» Correct Answer - A the complex formed by ammonia are [Ni(Nh3)6]+2 that is octahedral, Pt+2 shows coordination number 4 with Nh3, so complex is [pt(Nh3)4]+2 which is square planer, Zn+2 also shows 4 coordination number, [Zn(Nh3)4]+2 which is tetrahedral geometry
|
|
| 90. |
A substance is found to have a magnetic moments of `3.9BM`.How many unpaired electrons does it contain? |
| Answer» `mu_(B)=3.9" BM,n"=3` | |
| 91. |
The yellow colour solution of `Na_(2)CrO_(4)` changes to orange red on passing `CO_(2)` gas due to the formation of :-A. `CrO_(5)`B. `CrO_(3)`C. `Na_(2)Cr_(2)O_(7)`D. `Na_(3)CrO_(8)`. |
|
Answer» Correct Answer - C `CO_(2)+H_(2)OtoH_(2)CO_(3)hArr2H^(+)+CO_(3)^(2-),CrO_(4)^(2-)+2H^(+)hArrCr_(2)O_(7)^(2-)("orange red")+H_(2)O` |
|
| 92. |
State true or false: Reaction of `K_(2)Cr_(2)O_(7)` with cold and concentrated `H_(2)SO_(4)` yields bright orange/red precipitate of `CrO_(3)` write reactions invovled. |
| Answer» Correct Answer - 1 | |
| 93. |
Among the following series of transition metal ions the one where all meal ions have `3d^2` electronic configuration isA. `Ti^(+3),V^(+2),Cr^(+3),Mn^(+4)`B. `Ti^(+2),V^(+3),Cr^(+4),Mn^(+5)`C. `Ti^(+),V^(+4),Cr^(+6),Mn^(+7)`D. `Ti^(+2),V^(+3),Cr^(+2),Mn^(+3)` |
|
Answer» Correct Answer - 2 Electronic configuration of species. `._(22)Ti^(+2)=[Ar]3d^(2)4s^(@)` `._(23)V^(+3)=[Ar]3d^(2)4s^(@)` `._(24)Cr^(+4)=[Ar]3d^(2)4s^(@)` `._(25)Mn^(+5)=[Ar]3d^(2)4s^(@)` |
|
| 94. |
The basic character of the transition metal monoxide follows the orderA. `VO gt CrO gt TiO gt FeO`B. `CrO gt VO gt FeO gt TiO`C. `TiO gt FeO gt VO gt CrO`D. `TiO gt VO gt CrO gt FeO` |
|
Answer» Correct Answer - 4 The order of basic character of the transition metal monoxide is `TiOgtVOgtCrOgtFeO` because basic character of oxides decrease with increase in atomic number. Hence, oxides of transitional metals in low oxidation state `i.e. +2` and `+3` are generaly basic except `Cr_(2)O_(3)`. |
|
| 95. |
Ammonium dichromate is used in some fireworks. The green-coloured powder blown in the air isA. `CrO_(3)`B. `CuF_(3)`C. `MgF_(2)`D. `CuCl` |
|
Answer» Correct Answer - B |
|
| 96. |
How many of the followign are coloured or paramagnetic or coloured and paramagnetic both. `NO_(2),Cu^(+1),O_(2),O_(3),Hg_(2)^(+2),Cd^(+2), Al,C("graphite"),Sc^(+3)` |
|
Answer» Correct Answer - 4 `.^(**)NO_(2)` coloured & Pramagnetic `Cu^(+1)` Colourless `.^(**)O_(2)` Paramagnetic `O_(3)` Diagmagnetic `Hg_(2)^(+2)` Colourless `Cd^(+2)` Coloureless `.^(**)Al` Paramagnetic `.^(**)C("graphite")` Paramagnetic `Sc^(+3)` Colourless or diamagnetic |
|
| 97. |
`CuFeS_(2)+O_(2)("excess")overset(Delta)toX(s)+Y(s)` Note: Corresponding sulphates of copper and iron are formed respectively. which is correct chose for X and Y?A. X liberates iodine from soluble iodides like KlB. Y on heating liberates `SO_(3)` onlyC. X forms bluish white precipitate with sodium hydroxide which redissolves in excess of sodium hydroxide.D. Y on reaction with potassium ferricyanide gives brown precipitate. |
|
Answer» Correct Answer - A `CuFeS_(2)+4O_(2)overset(Delta)toCuSO_(4)(s)+FeSO_(4)(s)` ltbr (B) `2FeSO_(4)overset(Delta)toFe_(2)O_(3)+SO_(2)+SO_(3)` (C) `CuSO_(4)+2NaOHtoNa_(2)SO_(4)+Cu(OH)darr` (insoluble in excess NaOH) (D) `Fe^(2+)+2K_(3)[Fe(CN)_(6)]toFe_(3)[Fe(CN)_(6)]_(2)` (deep blue) |
|
| 98. |
`FeCr_(2)O_(4)+Na_(2)CO_(3)+O_(2)overset("Fusion")to[X]underset(H_(2)O)overset(H^(+))[Y]underset(H_(2)O_(2))overset(H^(+))to[Z]` Whichf of the following statement is true for the compounds [X], [Y] and [Z]?A. In all three compounds, the chromium is in +6 oxidation stateB. [Z] is a deep blueu-violet coloured compound which decomposes rapidly in aqueous solution into `Cr^(3+)` and dioxygen.C. Saturated solution of [Y] gives bright orange compound, chromic anhydride, with cold and concentrated `H_(2)SO_(4)`.D. All of these. |
|
Answer» Correct Answer - D `4FeCr_(2)O_(4)+8Na_(2)CO_(3)+7O_(2)overset(Fusion)Na_(2)overset(+VI)(CrO_(4))underset(H_(2)O)overset(H^(+))toNa_(2)overset(+VI)(Cr_(2))O_(7)underset(H_(2)O_(2))overset(H^(+))to overset(+VI)(Cr)O(O_(2))_(2)` (deep blue violet) `overset(H_(2)O)toO_(2)+H_(2)O+Cr^(3+)`. (X) (Y) (Z) `Na_(2)Cr_(2)O_(7)+H_(2)SO_(4)to2CrO_(3)` (bright orange/red-chromic anhydride) +`Na_(2)SO_(4)+H_(2)O`. |
|
| 99. |
When `KMnO_4` is added to oxalic acid, the decolourisation is slow in the beginning but becomes instantaneous after sometime becauseA. `Mn^(2+)` acts as autocatalystB. `CO_(2)` is formed as productC. Reaction is exothermicD. `MnO_(4)^(-)` catalyses the reaction |
|
Answer» Correct Answer - A |
|
| 100. |
Pick out the incorrect statementA. `MnO_(2)` dissolves in dilute HCl. But does not form `Mn^(4+)`B. MnO2 oxidises hot concentrated `H_(2)SO_(4)` liberating oxygenC. `K_(2)MnO_(4)` is formed when `MnO_(2)` is fused with KOH in presence of `KNO_(3)`D. Decomposition of `KMnO_(4)` is not catalysed by sunlight |
|
Answer» Correct Answer - D |
|