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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.
| 551. |
Thermodynamically the most stable form of carbon isA. DiamondB. GraphiteC. PeatD. Coal |
| Answer» Correct Answer - B | |
| 552. |
Which of the following molecules have zero dipole?A. `CS_(2)`B. `CO_(2)`C. `C Cl_(4)`D. `CH_(2)Cl_(2)` |
| Answer» Correct Answer - A::B::C | |
| 553. |
Which of the following statement is/are correct?A. `B(OH)_(3)` partially reacts with water to form `H_(3)O^(+)` and `[B(OH_(4))]^(-)` and behaves like a weak acidB. `B(OH)_(3)` behaves like a strong monobasic acid in presence of sugars and this acid can be titrated against NaOH solution using phenolphthalein as an indicatorC. `B(OH)_(3)` does not donate a proton and hence does not form any salt with NaOHD. `B(OH)_(3)` reacts with NaOH, forming `Na[B(OH)_(4)]` |
| Answer» Correct Answer - A::B::D | |
| 554. |
Which of the following compound react with `B_(2)H_(6)`?A. `Cl_(2)`B. `CO`C. `NH_(3)`D. `(CH_(3))_(3)N` |
| Answer» Correct Answer - A::B::C::D | |
| 555. |
Which of the following is not according to the priority stated against it ?A. `F_(2) gt Cl_(2) gt Br_(2) gt l_(2)` : bond dissociation enthalpyB. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` : Oxidising powerC. `HI gt HBr gt HCl gt HF` : acidic property in waterD. `F_(2) gt Cl_(2) gt Br_(2) gt I_(2)` : electronegativity. |
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Answer» Correct Answer - A Bond dissociation energy of `F_(2)` is less than that of `Cl_(2)` due to greater repulsion in the non-bonded electron pairs. |
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| 556. |
Which type of bond is present in Xe molecule ?A. CovalentB. Ion-dipoleC. van der WaalsD. dipole-dipole |
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Answer» Correct Answer - C Xenon atoms are linked to each other by van der Waals forces. |
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| 557. |
Chlorine reacts with excess of ammonia to form.A. `NH_(4)Cl`B. `N_(2)+HCl`C. `N_(2) + NH_(4)Cl`D. `N_(2) + NCl_(3)` |
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Answer» Correct Answer - C `8 NH_(3) +3Cl_(2) to N_(2) + 6 NH_(4)Cl` |
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| 558. |
Which of th efollowing reactions may be used for the laboratory prepartion of chlorineA. `NaCl+MnO_(2)+H_(2)SO_(4)(conc.)rarr`B. `Ca(OCl)Cl+H_(2)Orarr`C. `KMnO_(4)+HCl(Conc)rarr`D. Both (1) and (2) |
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Answer» Correct Answer - 4 Chlorine gas can be obtained in the laboratory by oxidizing concentrated hydrochloric with either managemenses (iv)Oxide (heat required) or potassium permanganate (no heat required): `Mn^(4+)(O^(2-))_(2)(s)+4H^(+)Cl^(-)(aq.)rarr Mn^(2+)(Cl^(-))_(2)(aq.)+2H_(2)O(l)+Cl_(2)(g)` `2K^(+)MnO_(4)^(-)(s)+16H^(+)CI^(-)(aq.)rarr2K^(+)CI^(-) (aq.)+2Mn^(2+)(Cl^(-))^(2)(aq.)+8H_(2)O(l)+5Cl_(2)(g)` Bleaching power also evolve chlorine when treated with ditute acid or carbon dioxide `Ca(OCl)_(2)+H_(2)SO_(4)rarrCaSO_(4)+H_(2)O+Cl^(2)` `Ca(OCl)_(2)+2HCl rarr CaCl_(2)+H_(2)O+Cl_(2)` `Ca(OCl)^(2)+CO_(2)rarrCaCO_(3)+Cl_(2)` |
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| 559. |
Potanium dischromate reacts with concrntrated hydrochloric acid to yieldA. `CIO_(2)`B. `KCIO_(2)`C. `CI_(2)`D. `CrO_(2)Cl_(2)` |
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Answer» Correct Answer - 3 Oxidizing agent potassium dichromate oxidizes hydrochloric acid to chlorine: `{:(K_(2)Cr_(2)O_(7)+8HCl rarr 2KCl +2CrCl_(3)+4H_(2)O+3[O]),(6HCl+3[O] rarr 3H_(2)O+3Cl_(2)),(bar(K_(2)Cr_(2)O_(7)+14 HCl rarr 2KCl+2CrCl_(3)+7H_(2)O+3Cl_(2))):}` Ozone also oxidizes `HCl` and `Cl_(2)` `O_(3)+2HCl rarr O_(2)+H_(2)O+Cl_(2)` Chlorine gas from any of these sources can be dried by passing it through concentrated sulphuric acid and collected by downwards delievery. |
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| 560. |
Which of the following chemical reaction is the safest laboratory prepartion of chlorine dioxide?A. `2HCIO_(3)+2HCIrarr2CIO_(2)+Cl_(2)+2H_(2)O`B. `2NaCIO_(3)+SO_(2)+H_(2)SO_(4)rarr underset("of NaCl")overset("trace")(rarr)2CIO_(2)+2NaHSO_(4)`C. `2NaCIO_(3)+2(COOH)_(2)underset(90^(@)C)overset(H_(2)O)(rarr)2CIO_(2)+2CO_(2)+(COONa)_(2)+2H_(2)O`D. All of these |
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Answer» Correct Answer - 3 Even through pure chlorine dioxide is explosive , it is of major industrial importantance. About `10^(6)` tones is produced every year worldwide .It is difficult to determine the exact production total, because the gas is so harzardous that it is generally produced in comparatively small quantities at the sites where it is to be used. The safest laboratory preparation is from sodium chlorate and oxalic acid ,as the automatically dilutes the gas with `CO_(2)` `2NaCIO_(3)+2(COOH)_(2) underset(90^(@)C)overset(H_(2)O) rarr 2CIO_(2)+2CO_(2)+(COONa)_(2)+2H_(2)O` The gas is made commercially from `NaCIO_(3)` .Teh synethetic reaction involves th ereduction chlorine in the `+5(CIO_(3)^(-))` oxidation state by chlorine in the `-1 (CI^(-))` oxidation state in very acid condition to give chlorine in the `+4 (CIO_(2))` and `0(CI_(2))` oxidation states: `2HCIO_(3)+2HCl rarr 2CIO_(2)+CI_(2)+2H_(2)O` or `2CIO_(3)^(-)(aq.)+4H^(+)2CI^(-)(aq.)rarr2CIO_(2)(g)+CI_(2)(g)+2H_(2)O(l)` In North america ,sulphur dioxide is added to reduce (and remove) the dichlorine gas to chloride ion,the sulfur dioxide is simultaneously oxidized to sulphate: `SO_(2)(g)+2H_(2)O(l)rarrSO_(4)^(2-)(aq.)+4H^(+)(aq.)+2e^(-)` `CI_(2)(g)+2e^(-)rarr2CI^(-)(aq.)` However this process produced sodium sulfate waste. Thus a pure product is formed by using `SO_(2)` `2NaCIO_(3)+SO_(2)+H_(2)SO_(4) overset("trace")underset("of "NaCl) rarr2CIO_(2)+2NaHSO_(4)` Using `HCI` causes contaminating with `CI_(2)` but his may be unimportant or even useful for bleaching and sterilization. A German process separates the dichlorine from the chlorine dioxide then reacts the dichlorine with hydrogen gas to produce hydrochloine acid.The acid can then reused in the synthasis. |
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| 561. |
Aqueous solution of ammonia consists ofA. `NH_(4)^(+)`B. `OH^(-)`C. `H^(+)`D. `NH_(4)^(+)` and `OH^(-)` |
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Answer» Correct Answer - 4 Ammonia is highly soluble in water. Its aqueous solution is weakly basic due to the presence of `OH^(-)` ions: `NH_(3)(g)+H_(2)O(l) hArr NH_(4) OH(aq) hArr NH_(4)^(+)(aq)+OH^(-)(aq)` |
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| 562. |
Chlorine dioxide reacts with ozone to yieldA. `Cl_(2)O_(7)`B. `Cl_(2)O_(6)`C. `CIO_(3)`D. `CIO` |
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Answer» Correct Answer - 2 `2CIO_(2)+2O_(3)rarrCI_(2)O_(6)+2O_(2)` It reacts with alkaIi as follows: `2CIO_(2)+2NaOH rarrNaCIO_(2)+NaCIO_(3)+H_(2)O` It is also used to manufacture sodium chlorine `NaCIO_(3)` which is also used for bleaching textiles and paper. `2CIO_(2)+2NaOH + H_(2)O_(2) rarr 2NaCIO_(2)+O_(2)+2H_(2)O` |
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| 563. |
Sulphur dioxide reacts with chlorine in the pressure of charcoal (Which acts as a catalyst) to giveA. thionyl chlorideB. sulphur dichloride and oxygenC. sulphuryl chlorideD. chlorine monoxide and sulphur |
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Answer» Correct Answer - 3 Sulphur dioxide undergoes addition reactions: `SO_(2)+Cl_(2)rarr underset("Sulphurly chloride")(SO_(2)Cl_(2))` Other examples are `2SO_(2)+O_(2) hArr 2SO_(3)` `PbO_(2)+SO_(2)rarrPbSO_(4)` |
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| 564. |
Ozone reach with KOH solution to yieldA. `K_(2)O`B. `KO_(2)`C. `K_(2)O_(2)`D. `KO_(3)` |
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Answer» Correct Answer - 4 Ozone reacts with `KOH` and forms potassium ozonide `(KO_(3))` , an orange coloured solid,which contains the paramagnetic `O_(3)^(-)` ion. `2KOH+5O_(3)rarr2KO_(3)+5O_(2)+H_(2)O` |
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| 565. |
when`P_(2)O_(5)` is heated with water the product isA. hyphosphoric acidB. phosphorous acidC. orthophosphoric acidD. hypophosphorous acid |
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Answer» Correct Answer - 3 `P_(4)O_(10) (or P_(2)O_(5))` an acidic oxide dissolve in water to yield phosphroic acid ( or orthosphoric acid `H_(3)PO_(4)`) `P_(4)O_(6)+6H_(2)Orarr4H_(3)PO_(4)` On the other hand `P_(4)O_(6) (or P_(2)O_(3))` yields phosphorous acid `P_(4)O_(6)+6H_(2)Orarr4H_(3)PO_(3)` |
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| 566. |
In the presence of water, sulphur is oxidized by ozone to yieldA. `SO_(3)`B. `H_(2)SO_(4)`C. `SO_(2)`D. `H_(2)SO_(3)` |
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Answer» Correct Answer - 2 Moist sulphur is oxidized to sulphuric acid: `S+H_(2)O+3O_(3)rarrH_(2)SO_(4)+3O_(2)` Similarly ,moist phosphorus,arsenic and iodine are oxidized to their corrosponding oxyacids: `2P+3H_(2)O+5O_(3)rarr2H_(3)PO_(4)+5O_(2)` `2As+3H_(2)O+5O_(3)rarr2H_(3)AsO_(4)+5O_(2)` `O_(3)rarrO_(2)+Oxx5` `(I_(2)+H_(2)O+5Orarr2HIO_(3))/(I_(2)+H_(2)O+5O_(3)rarr2HIO_(3)+5O_(2))` |
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| 567. |
Ozone reacts with neutral KI solution to yieldA. `I_(2)`B. `O_(2)`C. `I_(2)` and `O_(2)`D. `KOH, I_(2)` and `O_(2)` |
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Answer» Correct Answer - 4 Due to its ease with which it can liberate nascent oxygen,it acts as an extermely powerful oxidizing agent,second only to `F_(2)` in oxidizing power and reacts much more readily than oxygen. The potential equation is `O_(3)rarrO_(2)+O` It liberates iodine from neutral `Kl` solution: `O_(3)rarrO_(2)+O` `(2KI+H_(2)O+Orarr2KOH+I_(2))/(2KI+H_(2)O+Orarr2KOH+I_(2)+O_(2)` It oxidies `HX` into `X_(2)[X is Cl,Br,or I]` `O_(3)rarrO_(2)+O` `(2HX+OrarrH_(2)O+X_(2))/(2HX+O_(3)rarrH_(2)O+X_(2)+O_(2))` Acidified ferrous sulphate to ferric sulphate `O_(3)rarrO_(2)+O` `(2FeSO_(4)+H_(2)SO_(4)+OrarrFe_(2)(SO_(4))_(3)+H_(2)O)/(2FeSO_(4)+H_(2)SO_(4)+O_(3)rarrFe_(2)(SO_(4))_(3)+H_(2)O+O_(2))` Oxidizes lead sulphide (black)to lead sulphate (white) `O_(3)rarrO_(2)+Oxx4` `(Pbs+4OrarrPbSO_(4))/(PbS+4O_(3)rarrPbSO_(4)+4O_(2))` Similarly,`CuS,ZnS`, and `CdS` are oxidized to`CuSO_(4),ZnSO_(4)` and `CdSO_(4)` respectively. Other example are `underset("nitrite")(NaNO_(3))+O_(3)rarrunderset("nitrate")(NaNO_(3))+O_(2)` `underset("Sulphite")(Na_(2)SO_(3))+O_(3)rarrunderset("Sulphate")(Na_(2)SO_(4))+O_(2)` `underset("asernite")(Na_(3)AsO_(3))+O_(3)rarrunderset("arsenate")(Na_(3)AsO_(4))+O_(2)` `underset("manganate")(2K_(2)MnO_(4))+H_(2)O+O_(3)rarrunderset("permanganate")(2KMnO_(4))+2KOH+O_(2)` `underset("ferricyanide")(2K_(4)[Fe(CN)_(6)])+H_(2)O+O_(3)rarrunderset("ferricyanide")(2K_(3)[Fe(CN)_(6)])+2KOH+O_(2)` |
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| 568. |
`PH_(4)I+NaOH rarr`? The product isA. `P_(4)O_(10)`B. `P_(4)O_(6)`C. `NH_(3)`D. `PH_(3)` |
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Answer» Correct Answer - 4 The impure phosphine gas may be purified by treating it with hydrogen iodide followed by heating the phosphonium iodide thus formed with caustic soda solution `PH_(3)+HI rarr PH_(4)I` `PH_(4)I+NaOH rarr PH_(3)+NaI+H_(2)O` |
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| 569. |
`PCI_(3)` reacts with water to yieldA. `H_(3)PO_(4)`B. `H_(3)PO_(3)+HCl`C. `POCl_(3)`D. `PH_(3)` |
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Answer» Correct Answer - 2 Phosphorus trichloride `(PCl_(3))` reacts violently with water to yield phosphorous acid `(H_(3)PO_(3))` and hydrochloric acid: `PCl_(3)+3H_(2)O rarr H_(3)PO_(3)+3HCl` |
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| 570. |
There is a small increase in atomic radius in moving from P to As in group 15 elements as compared to large increase in atomic radius in moving from N to P in the same group. Explain. |
| Answer» The atomic radii of the three elements are : N (70 pm), P(110 pm) and As (121 pm). In moving from N to P, there is effective shielding by intervening s and p-electrons while it is comparatively poor by intervening d-electrons which are involved in moving from P to As. As a result, the increse in atomic radius is less in this case. | |
| 571. |
How would you explain the lower atomic radii of `Ga` as compared to `Al`?A. poor screening effect of d-electrons for the outer electrons from increased nuclear chargeB. increased force of attraction of increased nuclear charge on electronsC. increased ionisation enthalpy of Ga as compared to AlD. anomalous behaviour of Ga. |
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Answer» Correct Answer - A Presence of 10 d-electrons in gallium which have poor screening effect on the outer electrons increases the force of attraction between the outermost electrons and nuclear charge resulting in decreases in atomic radius. |
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| 572. |
The order of catenation power is |
| Answer» Correct Answer - CgtSigtGegtSngtPb | |
| 573. |
Which of the following group `13` elements forms univalent halides which are more stable than the trihalides?A. `Al`B. `Ga`C. `Tl`D. `In` |
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Answer» Correct Answer - C The oxidation number `(+1)` is the most stable for `Tl`. Thus, thallium forms univalent thallous halides which are more stable than thallium trihalides. This illustrates the inert pair effect. `TIF` is ionic. `Al, Ga` and In all form monohalides `MX` in the gas phase at elevated temperatures: `AlCl_(3) + 2Al underset("temperature")overset(High)rarr 3AlCl` However, these compounds are not very stable and are covalent. `B` forms several stable polymeric monohalides `(BX)_(n)`. |
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| 574. |
Match the column I and column II and mark the appropriate choice. A. `(A) rarr (i), (B) rarr (iii), (C) rarr (ii), (D) rarr (iv)`B. `(A) rarr (ii), (B) rarr (iv), (C) rarr (iii), (D) rarr (i)`C. `(A) rarr (iii), (B) rarr (ii), (C) rarr (iv), (D) rarr (i)`D. `(A) rarr (iv), (B) rarr (i), ((C)) rarr (ii), (D) rarr (iii)` |
| Answer» Correct Answer - C | |
| 575. |
Nitrous oxide `(N_(2)O)` is prepared by heatingA. a solution of ammonium nitrate acidified with `HCI`B. lead nitrateC. potassium nitrateD. ammonium nitrite |
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Answer» Correct Answer - 1 An explosion can ensue from strong heating of ammonium nitrate. Thus, a safer method is to heat an ammonium nitrate solution that has been acidified with hydrochloric acid: `NH_(4)NO_(3)(aq.)overset(H^(+))rarrN_(2)O(g)+2H_(2)O(l)` |
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| 576. |
Covalency of oxygen cannot exceed 2 unlike sulphur which can show +4 or +6 becauseA. oxygen atom does not have d-orbitalsB. oxygen atom has two unpaired electrons in its valence shellC. oxygen can form a double bond with another oxygen atomD. electrons of oxygen atom cannot be promoted to d-orbitals due to its small size. |
| Answer» Correct Answer - A | |
| 577. |
The most stable oxidation states of nitrogen areA. `-3,+3,`and `+5`B. `-3,+3`and `-5`C. `-3, 0` and `+3`D. `0, +3`,and `+5` |
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Answer» Correct Answer - 1 Through nitrogen exhibits a wide range of oxidation states `(-3" to "+5)`, but the most abundant and stable oxidation states are `-3,+3`, and `+5`. |
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| 578. |
Which of the following halides of nitrogen is stable?A. `NF_(3)`B. `NI_(3)`C. `NBr_(3)`D. `NCl_(3)` |
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Answer» Correct Answer - 1 `NF_(3)` behave differently form the others. It is unreactive ,rather like `CF_(4)` and does not hydrolyse with water, dilute acids or alkali. It does react if sparked with water vapour. `2NF_(3)+3H_(2)Orarr6HF+N_(2)O_(3)` The instability of `NCl_(3), NBr_(3)` and `NI_(3)` is because of the weakness of `N-X` bond due to large difference in the size of `N` and `X` atoms. On the other hand ,`N-F` bond is quite strong because the difference is size of `N (75p m)` and `F(72p m)` is small, Consequently ,`NF_(3)` is an exothermic compound which accounts for the stability of `NF_(3)` |
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| 579. |
Why is+2oxidiation state of lead more stable than +4 oxidation state? |
| Answer» Due to inert pair effect. | |
| 580. |
The elements that has the maximum tendency to show the inert pair effect isA. `Bi`B. `Sb`C. `As`D. `N` |
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Answer» Correct Answer - 1 All the element of group `15` have five electrons in their valence shell they exhibits a highest oxidation state of `+5` by using all five electrons in forming bonds. As one goes down , the tendency of the pairs of ns electrons to remain inert (inert pair effect) increases and only np electrons are used in bonding ,resulting in an oxidation state of `+3` The stability of `+3` state relative to the `+5` state thus increases on moving down the group. Arsenic and antimony (`V`) oxides can be obtained by oxidation of the element with concentrated nitiric acids: `2Sb(s)+10HNO_(3)(a.q.)rarr Sb_(2)O_(5)(s)+5H_(2)O(l)+10NO_(2)(g)` Both the oxides are unstable with respect to the `3`-valent state , decomposing into the `3`- valent oxide and oxygen occurring on gentle heating: `2As_(2)O_(5)(s)rarrAs_(4)O_(6)(s)+2O_(2)(g)` It is possible that `Bi(V)`oxide exists,although it has never been obtained in a pure form.In the view of the instability of the `5`- valent oxides of `As` and `Sb` to mind heating and the increased metallic character of `Bi`, it would be expected to be very unstable with respect to `Bi(III)` oxide. Thus `N` showes the least tendency to show the inert pair effect while `Bi` shows the most tendency to exhibit inert pair effect. |
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| 581. |
Which of the following are ionic compounds?A. `NF_(3)`and`PF_(3)`B. `PF_(3)`and`AsF_(3)`C. `AsF_(3)`and`SbF_(3)`D. `SbF_(3)`and`BiF_(3)` |
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Answer» Correct Answer - 4 The energy required to produce `E^(5+)` is so immense that it is never formed by any Group `15` element. The compounds formed by these elements in `+5` oxidation state are thus perdominantly covalent However, in case of `Sb` and `Bi` the sum of the first three ionization enthaipies is just low enough to form `E^(3+)` ions. since `F` is the most electronegative element, it provides an electronegative difference large enough tp permit the formation of ionic bonds. Thus, `SbF_(3)` and `BiF_(3)` and exist as ionic solids. |
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| 582. |
The oxidation state of -3 is least stable inA. `As`B. `P`C. `Bi`D. `Sb` |
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Answer» Correct Answer - 3 Because`Bi` a true metal and is the least electronegative element of the family. |
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| 583. |
The reason for small radius of Ga compared to Al is ……..A. poor screening effect of d and f-orbitalsB. increase in nuclear chargeC. presence of higher orbitalsD. higher atomic number |
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Answer» Correct Answer - A::B On moving down the group from Al to Ga, atomic radius decrease (exception) due to poor shielding by d-electrons. On moving form Al to Ga, shielding effect n d-electrons is unable to compensate increased nuclear charge. Hence, successive increase of atomic radius as expected is not observed. |
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| 584. |
Which of the following is known as pseudo alum?A. `KMn(SO_(4))_(2).12H_(2)O`B. `KCr(SO_(4))_(2).12H_(2)O`C. `NH_(4)Fe(SO_(4))_(2).12H_(2)O`D. `FeSO_(4).Al_(2)(SO_(4))_(3).24H_(2)O` |
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Answer» Correct Answer - D Alums are double salts of the general formula `H_(2)SO_(4) . R_(2)(SO_(4))_(3) . 24H_(2)O` where `M` is a univalent ion such as `Na^(+) , K^(+)`, or `NH_(4)^(+)` and `R` is a trivalent ion such as `Al^(3+)` or `Cr^(3+)` . On the other hand, pseudo alum has the general formula `MSO_(4) . R_(2)(SO_(4))_(3) . 24H_(2)O` where `M` is a divalent ion such as `Fe^(2+)`. Therefore, `FeSO_(4) . Al_(2)(SO_(4))_(3) . 24H_(2)O` is a pseudo alum. |
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| 585. |
Major constituent of biogas isA. `CH_(4)`B. `CO`C. `C_(2)H_(6)`D. `C_(4)H_(10)` |
| Answer» The mixture of gases that can burn and produce heat energy, which is emitted from a place where organic wastes (like animal dung, human excreta, vegetable waste, leaves, etc) decay out of contact of air, is called biogas or gobar gas. Its main constituent is `CH_(4) (60 - 70%)`. Other gases present are `CO, H_(2), CO_(2), H_(2)S, N_(2)`, etc. | |
| 586. |
The strongest reducing agent amongest all the hydrides of Group `15`element isA. `BIH_(3)`B. `PH_(3)`C. `NH_(3)`D. `AsH_(3)` |
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Answer» Correct Answer - 1 The tendency to liberate hydrogen inceases as we move from `NH_(3)` to `BIH_(3)`. This happen beacause the size of the central atom increases as we move down the group. Consequently ,its tendency to form strong covalent bond with realtively small `H` atom decreases. Consequently , the reducing character of the hydrides (i.e ability to release hydrogen ) increases on moving down the group. Ammonia is only a mild reducing agent while `BiH_(3)` is the strongest reducing agent amongst all the hyderides. |
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| 587. |
Each of the following is true for white and red phosphorus except that theyA. are both soluble in `CS_(2)`B. can be oxidized by heating in airC. consist of the same kind of atomsD. can be converted into one another. |
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Answer» Correct Answer - A White phosphorus is soluble in `CS_(2)` whereas red phosphorus is insoluble in `CS_(2)`. |
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| 588. |
Which of the following hydries has the highest dipole moments?A. `SbH_(3)`B. `AsH_(3)`C. `PH_(3)`D. `NH_(3)` |
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Answer» Correct Answer - 4 As the electronegativity of the central atom (`E`) decreases, the dipole moment of the hydride `(EH_(3))` shows a correspponding decrease. |
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| 589. |
Which of the following is true for white and red phosphours except that theyA. canbe converted into one anotherB. consist of the same kind of atomsC. can be oxidized by heating in airD. both are soluble in `CS_(2)` |
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Answer» Correct Answer - 4 White phosphours is insoluble in water but is soluble in organic solvents such as `CS_(2)`, alcohol and other. On the other handd, red phosphours is insoluble in water as well as inorganic solvents such as `CS_(2)` alcohol and ether as its `P_(4)` tetrahedra are joined together through covalent bonds. |
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| 590. |
Biogas and producer gas are made up of more than one gaseous substances. Which of the following is correct?A. Biogas contains `CO_(2)` but producer gas does not.B. Producer gas contains `CO` but not `CO_(2)`C. Both biogas and producer gas have `N_(2)`D. All of the three above |
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Answer» Correct Answer - D Biogas (or gobar gas) is a mixture of `CH_(4), CO, H_(2), CO_(2), H_(2)S`, and `N_(2)` while producer gas is a mixture of `CO` and `N_(2)`. |
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| 591. |
Heavier elements of `p`-block in each group do not formA. `p_(pi) - p_(pi)` multiple bondsB. `d_(pi) - p_(pi)` multiple bondsC. `d_(pi) - d_(pi)` multiple bondsD. all of these |
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Answer» Correct Answer - A Due to large size of their atoms, `p_(pi) - p_(pi)` multiple bonds are not formed by heavier elements. Remember, pi bonds are weaker (than `sigma` bonds). Thus, if orbitals are large, `p_(pi) - p_(pi)` multiple bonds are not formed. |
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| 592. |
Which of the following name-formula combinations is wrongly matchedA. Metaphosphoric acid `rarr(HPO_(3))_(n)`B. Pyrophosphoric acid `rarrH_(4)P_(2)O_(7)`C. Pyrophosphoric acid `rarrH_(4)P_(2)O_(5)`D. Orthophosphoric acid `rarrH_(3)PO_(3)` |
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Answer» Correct Answer - 4 `H_(3)PO_(4)` is orthophosphorous acid (phosphonic acid). Orthophosphoric acid is `H_(3)PO_(4)`. In oxoacids `P`atom is tetrahedrally surrounded by other atoms. All these acids contain one `P=O` and at least one `P-OH` bond. The oxoacids in which `P` atom has lower oxidation number (less then+5)contains (in addition to`P=O` and `P-OH` bonds)either`P-P` (e.g, in `H_(2)P_(2)O_(6)` or `P-H` (e.g.,in `H_(3)PO_(3)`) bonds but not both. Oxoacids having `+3` oxidation state tend to disproportionate to higher and lower oxidation states. For example ,orthophosphorous acid(or phosphorus acid)on heating disproportions to give orthophosphrous acid (or phosphoric acid)and phosphine. `4H_(3)PO_(3)+3H_(3)PO_(4)+PH_(3)` |
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| 593. |
Which of the following oxoacide of phosphorus is a reducing agent and a monobasic acid as well?A. Orthophosphorous acid `(H_(3)PO_(3))`B. Orthophosphoric acid `(H_(3)PO_(4))`C. Hypophosphorous acid `(H_(3)PO_(2))`D. Cyclotrimetaphosphoric acid, `(HPO_(3))_(3)` |
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Answer» Correct Answer - 3 The oxoacids which contain `P-H` bond have strong reducing properties. Thus ,hypophosporous acid is a good reducing agent as it contains two `P-H` bonds. For example ,it reduces silver nitrate to metallic silver. `4AgNO_(3)+2H_(2)O+H_(3)PO_(2)rarr4Ag+4HNO_(3)+H_(3)PO_(4)` The `P-H` bonds are not ionisable to give `H^(+)` and do not play any role in basicity. Only those `H` atoms which are attached with oxygen in `P-OH` bonds are ionisable and cause bacity .Thus ,hyprophosphorous is monobasic as its structure has only one `P_OH` bond. On the other hand, `H_(3)PO_(3)` and `H_(3)PO_(4)` are dibasic and tribasic,respectively as the structure of `H_(3)PO_(3)` has two `P_OH` bonds and `H_(3)PO_(3)` three. |
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| 594. |
Name two compounds in which oxygen has oxidation states different from `-2`. |
| Answer» `OF_(2)(+), H_(2)O(-1)` | |
| 595. |
How does ammonia react with a solution of `Cu_(2)^(+)`? |
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Answer» `NH_(3)` acts as a Lewis base. It donates its electron pair and forms a linkage with metal ion. `underset("Bule")(Cu_((aq))^(2+)) + 4 NH_((aq))^(3) harr underset("Deep bule") ([Cu(NH_(3))_(4)]_((aq))^(2+))` |
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| 596. |
How does ammonia react with blue solution having `Cu^(2+)` ions ? |
| Answer» `underset(("blue"))(Cu^(2+))(aq)+4NH_(3)(aq)hArr underset(("Deep blue"))([Cu(NH_(3))_(4)]^(2+)(aq))` | |
| 597. |
which of the following minerals is known asn orpiemnt?A. `As_(2)S_(3)`B. `As_(4)S_(4)`C. `HgS`D. `PbS` |
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Answer» Correct Answer - 1 Many minerals are sulphide ores. The most common of these are listed in given table. `|{:("Formula","Common name","Systematic name."),(HgS,"Cinnabar","Mercury" (II) "sulphide"),(Pbs,"Galena","Lead" (II) "sulphide"),(FeS_(2),"Pyrite","Iron" (II) "sulphide"),(ZnS,"Sphalerite","Zinc sulphide"),(As_(2)S_(3),"Orpiment","Diarsenic trisulphide"),(Sb_(2)S_(3),"Stibnite","Diantimony trisulphide"),(CuFeS_(2),"Chalcopyrite","Copper" (II) "iron" (II) "sulphide"):}|` Orpiment a yellow mineral ,is natural arsenic trisulphide `(As_(2)S_(3))` while realgar a red mineral ,is natural tetrarsenic tetrasulphide `(As_(4)S_(4))` Sulphides tend to be used for specialized purposes.The intense black antimony trisulphide `(Sb_(2)S_(3))` was one of the first cosmetic,being used as eye shadow from earliest recorded times Today sodium sulphide is the sulphide in highest demand between `10^(5)` and `10^(6)` tonnes is produced every year by the high temperatuer reduction of sodium sulphate with coke: `Na_(2)SO_(4)(s)+2C(s)rarrNa_(2)S(l)+2CO_(2)(g)` Sodium sulphide is used to remove hair form hides in the tanning of leather it is also used in ore separation by floation for the manufacture of sulphur containing dyes ,and in the chemical industry, such as the precipitaiton of toxic metal ions ,particularly lead. Other sulphides in commercial used are selenium disulphide `(SeS_(2))` a common additive to antisandruff hair sampoos and moluybdenum `(IV)` sulphide `(MoS_(2))`, an excellent lubricant for metal surfaces ,either on its own or suspended in oil. Metal sulphides tend to be dense, opaque solids , and it is this property that makes the bright yellow cadumium sulphide `(CdS)` a popular pigment for oil painitng. |
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| 598. |
`NO_(2)` is easilyA. oxidized to `NO_(3)^(-)` and reduced to `NO`B. oxidized to `NO_(2)^(+)` and reduced to `NO_(2)^(-)`C. oxidized to `NO_(3)^(-)` and reduced to `N_(2)`D. oxidized to `NO_(2)^(+)` and reduced to `NH_(3)` |
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Answer» Correct Answer - 2 `NO_(2)` is an odd electron molecules. By losing the unpaired electron it is oxidized to `NO_(2)^(+)` and by gaining an electron it is reduced to `NO_(2)^(-)` |
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| 599. |
Number of points at which tetrahedral units are linked in pyrosilicates isA. Five ponitB. Six pointC. Two pointD. One point |
| Answer» Correct Answer - D | |
| 600. |
Assertion: Ammonia acts as a ligand. Reason : A lone pair of electrons on nitrogen can be donated to acceptor.A. If both assertion and reason are true and reason is the correct explanation of assertion.B. If both assertion and reason are true but reason is not the correct explanation of assertion.C. If assertion is true but reason is false.D. If both assertion and reason are false. |
| Answer» Correct Answer - A | |