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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.
| 101. |
Select the correct statement(s)A. In group III, `Fe^(3+)` and `Cr^(3+)` can be differentiated by increasing `NH_(4)^(+)` ion concentrationB. In `V^(th),Na_(2)CO_(3)` is added to precipitate out only the carbonates of `Ba^(2+),Sr^(2+)` and `Ca^(2+)`C. Like brown ring test, diphenylamine test is given only by salts containing `NO_(3)^(-)`D. Sodium chloride on heating with aqueous solution of `K_(2)Cr_(2)O_(7)` and concentrated `H_(2)SO_(4)` produces deep vapour |
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Answer» Correct Answer - A (A)`Cr^(3+)+3NH_(3)+3H_(2)OtoCr(OH)_(3)darr+3NH_(4)^(+)` The reaction is reversible, on addition of `NH_(4)^(+)` shifts to backward direction.Thus if excess of `NH_(4)^(+)` salt is added, then precipitation of `Cr(OH)_(3)` will not take place. However because of very small `k_(sp` of iron `(III)` hydroxide complete precipitation will take place even in the presence of ammonium salts. `(k_(sp)=3.8xx10^(-38))` (B)Concentration of `CO_(3)^(2-)` provided by `Na_(2)CO_(3)` in aqueous solution is just sufficient to precipitate `Mg^(2+)` ion as `MgCO_(3)` along with `Ba^(2+),Ca^(2+)` and `Sr^(2+)` as their carbonates. (C )The oxidising anions like `MnO_(4)^(-),Cr_(2)O_(7)^(2-), CIO_(4)^(-)` etc also respond to this test. (D)`CrO_(2)Cl_(2) +2H_(2)O to H_(2)CrO_(4)(aq)+2HCl` |
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| 102. |
Aqueous solution of a salt when treated with `AgNO_(3)` solution gives a white precipitate , white dissolves in `NH_(4)OH`. Radical present in the salt isA. `Cl^(-)`B. `S^(2-)`C. `I^(-)`D. All of them |
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Answer» Correct Answer - A When `Cl^(-)` is treated with `AgNO_(3)` solution in presence of dilute `HNO_(3)`, corresponding silver halide is obtained which is soluble in `NH_(4)OH, NaCN,` and `Na_(2)S_(2)O_(3)`. `AgNO_(3)+NaClrarr AgClunderset("white")(+)NaNO_(3)` `AgCl+"dil. " 2NH_(4)OH underset("complex")([Ag(NH_(3))_(2)Cl)+ 2H_(2)O` |
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| 103. |
Which of the following reagents can be used for making the distinction between `AgCl` and `Agl`?A. Sodium arsenite solutionB. Dilute ammonia solutionC. Potassium cyanide solutionD. Dilute `HNO_(3)` |
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Answer» Correct Answer - A,B (A)`3AgCldarr+AsO_(3)^(3-)toAg_(3)AsO_(3)darr ("yellow")+3Cl^(-)` `Agl` is unaffected by this treatment. (B)`AgCl+2NH_(3)to[Ag(NH_(3))_(2)]Cl` `Agl` is not soluble in dilute ammonia solution. ( C)Both soluble in potassium cyanide, forming soluble complexes. (D)Both insoluble in dilute `HNO_(3)` |
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| 104. |
Is their any reaction other then cyanide reaction which can be used for the differentiation of `Cu^(2+)` and `Cd^(2+)` ions ? |
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Answer» Yes.By the reaction of ammonia according to the following reactions. `Cu^(2+)+4NH_(3)to[Cu(NH_(3))_(4)]^(2+)` (deep blue solution) `Cu^(2+)+4NH_(3)to[Cu(NH_(3))_(4)]^(2+)` (colourless solution) |
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| 105. |
What happens when ammonium sulphide solution reacts with a solution containing a `Cr(III)` salt? |
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Answer» Salt hydrolyses to `Cr(OH)_(3) darr` `2 Cr^(3+)+3S^(2-)+6H_(2)Oto2Cr(OH)_(3)+darrH_(2)S` |
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| 106. |
The following can be used to regulate the concentration of `OH^(-)` ions for the scheme of basic radical analysis (`III` group)A. `NH_(4)NO_(3)`B. `NH_(4)Cl`C. `(NH_(4))_(2)SO_(4)`D. `(NH_(4))_(2)CO_(3)` |
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Answer» Correct Answer - A,B `(NH_(4))_(2) CO_(3)` and `(NH_(4))_(2) SO_(4)` can not be used as they would also precipitate the `IV` and `V^(th)` group cations. |
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| 107. |
An aqueous solution of salt containing an acidic radical `X`-reacts with sodium hypochlorite in neutral medium. The gas evolved produces blue black colour spot on the starch paper.The anion `X^(-)` is:A. `CH_(3)COO^(-)`B. `Br^(-)`C. `I^(-)`D. `NO_(2)^(-)` |
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Answer» Correct Answer - C `OCl^(-)+3l^(-)+H_(2)Otol_(3)^(-)+2OH^(-)+Cl^(-)` `l_(3)^(-)+` starch `to` blue-black spot on starch paper due to the formation of iodine-starch adsorption complex. |
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| 108. |
In which reagents the `AgCl` precipitate is soluble? |
| Answer» In ammonia solution, potassium cyanide solution and sodium thiosulphate solution forming `[Ag(NH_(3))_(2)]Cl,K[Ag(CN)_(2)]` and `Na_(3)[Ag(S_(2)O_(3))_(2)]` soluble complexes respectively. | |
| 109. |
Which basic radical is tested with the help of alkaline sodium stannite? |
| Answer» `Bi^(3+),Bi^(3+)+3OH^(-)toBi(OH)_(3)darr,2Bi(OH)_(3)darr+3[Sn(OH)_(4)]^(2-)to2Bi darr ("black")+3[Sn(OH)_(6)]^(2-)` | |
| 110. |
White precipitate of `AgCl` turns to greyish or black when:A. reacts with `Na_(3)AsO_(4)`B. exposed to sunlightC. reacts with `K_(2)CrO_(4)`D. reacts with concentrated `HCl` |
| Answer» Correct Answer - B | |
| 111. |
An aqueous solution of a substance gives a white percipitate on treatment with dil `HCl`, which dissole on heating. On passing `H_(2)S` in hot acidic solution a black percipitate is formed. The substance is:A. `Hg_(2)^(2+)` saltB. `Cu^(2+)` saltC. `Ag^(+)` saltD. `Pb^(2+)` salt |
| Answer» Correct Answer - 4 | |
| 112. |
A gas X is passed through water to form a saturated solution. The aqueous solution on treatment with silver nitrate gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas Y. Identify X and Y.A. `X = CO_(2), Y = Cl_(2)`B. `X = Cl_(2), Y = CO_(2)`C. `X = Cl_(2), Y = H_(2)`D. `X = H_(2), Y = Cl_(2)` |
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Answer» Correct Answer - C |
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| 113. |
A gas X is passed through water to form a saturated solution. The aqueous solution on treatment with silver nitrate gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas Y. Identify X and Y.A. `X=CO_(2),Y=Cl_(2)`B. `X=Cl_(2),Y=CO_(2)`C. `X=Cl_(2),Y=H_(2)`D. `X=H_(2),Y=Cl_(2)` |
| Answer» Correct Answer - 3 | |
| 114. |
An aqueous solution of a metal nitrate yields a white precipitate on treatment with aqueous `Na_(2)SO_(3)` solution. Precipitate dissolves in `NaOH(aq)` solution forming a complex anion X. Also, the orginal sample of solution yields a white precipitate on treatment with dilute `HCl` solution, which dissolves in boiling water. The most likely formula of the complex anion (X) isA. `[Ag(OH)_(2)]^(-)`B. `[Ag(OH)_(4)]^(-)`C. `[Zn(OH)_(4)]^(2-)`D. `[Pb(OH)_(4)]^(2-)` |
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Answer» Correct Answer - D |
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| 115. |
Which of the following statement is correct?A. `Fe^(2+)` gives brown colour with ammonium thiocyanateB. `Fe^(2+)` gives blue precipitate with potassium ferricyanideC. `Fe^(3+)` gives brown colour with potassium ferricyanideD. `Fe^(3+)` gives red colour with potassium ferrocyanide |
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Answer» Correct Answer - B::C |
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| 116. |
How many of the following liberate coloured vapour/gas with concentrated `H_(2)SO_(4)`? `KCl(s)+K_(2)Cr_(2)O_(7)(s), KNO_(2)(s),Kl(s), KBr(s),KCl(s)` `KBr(s)+MnO_(2)(s),KNO_(3),KCl(s)+MnO_(2),K_(2)SO_(3)` |
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Answer» Correct Answer - 7 (i)`4Cl^(-)+Cr_(2)O_(7)^(2-) +6H^(+) to 2CrO_(2)Cl_(2) uarr ("deep red")+3H_(2)O` (ii)`NO_(2)^(-)+H^(+) to HNO_(2) , 3HNO_(2) to HNO_(3)+NO uarr +H_(2)O` `2NO uarr +O_(2) uarr to NO_(2) uarr` (brown) (iii)`3l^(-)+2H_(2)SO_(4) to l_(3)^(-) uarr ("violet") +SO_(4)^(2-) +2H_(2)O+SO_(2)` (iv)`2KBr +2H_(2)SO_(4) to Br_(2) uarr ("reddish brown")+SO_(2) uarr +NO_(4)^(2-) + 2K^(+) + 2H_(2)O` (v)`Cl^(-)+H_(2)SO_(4) to HCl uarr ("colourless") + HSO_(4)^(-)` (vi)`2KBr + MnO_(2) + 2H_(2)SO_(4) to Br_(2) uarr ("reddish-brown")+2K^(+)+Mn^(2+)+2SO_(4)^(2+) +2H_(2)O` (vii)`4NO_(3)^(-) + 2H_(2)SO_(4) to Br_(2) uarr ("reddish-brown") + 2K^(+) +MN^(2+)+2SO_(4)^(2-) + 2H_(2)O` (viii)`KCl + MnO(OH)_(2) +2H_(2)SO_(4)+2Cl^(-)("brown") to Mn^(2+)+Cl_(2) uarr ("yellowish green") + 2SO_(4)^(2-)+3H_(2)O` (ix)`SO_(3)^(2-) + 2H^(+) to SO_(2) uarr ("colourless") + H_(2)O` |
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| 117. |
Passing `H_(2)S` gas in slightly acidic solution of a metal nitrate results in formation in formation of a black coloured precipitate (X). The precipitate is insoluble in cold-dilute acid solution as well as in ammonium sulphide solution. Boiling, concentrated `HCl` dissolves X, evolving a pungent smelling gas .Hot, dilute `HNO_(3)` dissolves the precipitate, leaving behind a white precipitate (Y). Boiling the solution for a longer time dissolves Y too. The most likely density of X and Y areA. `CuS` and SB. `Bi_(2)S_(3)` and SC. `PbS` and SD. `Ag_(2)S` and S |
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Answer» Correct Answer - B |
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| 118. |
A black coloured compound `(A)` on reaction with dilute `H_(2)SO_(4)` gives a gas `(B)` which on passing in a solution of an acid `( C)` gives a white turbidity `(D)`.Gas `(B)` when passed in an acidified solution of a compound `(E)` gives a precipitate `(F)` soluble in dilute `HNO_(3)`.After boiling this solution when an excess of `NH_(4)OH` is added a intense blue coloured compound `(G)` is formed. To this solution on addition of acetic acid and aqueous `K_(4)[Fe(CN)_(6)]` a chocolate brown precipitate `(H)` is obtained.On addition of an aqueous solution of `BaCl_(2)` to an aqueous solution of `(E)` a white precipitate insoluble in dilute `HCl` is obtained. Identify the compounds from `(A)` to `(H)`. |
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Answer» Correct Answer - A-`FeS,CuS , PbS, HgS , CoS, NiS` , B-`H_(2)S` , C-`HNO_(3)` D-`S` , E-`CuSO_(4)` , F-`CuS` G-`[Cu(NH_(3))_(4)](NO_(3))_(2)` `CuS+H_(2)SO_(4) to CuSO_(4)+H_(2)S` `2HNO_(3) to 2NO_(2)+H_(2)O+[O]` `H_(2)S+[O]to H_(2)O+S darr ("white")(HNO_(3)` is strong oxidising agent). `CuSO_(4)+H_(2)S to CuS darr +H_(2)SO_(4)` `3CuS + 8HNO_(3) to 3Cu^(2+) + 6NO_(3)^(-)+3S darr +2NO uarr+4H_(2)O.` `2NO_(3)^(2-)+Cu^(2+) +4NH_(4)OH to [Cu(NH_(3))_(4)]^(2+) (NO_(3))_(2)` (intense blue coloured solution )+`4H_(2)O` `[Cu(NH_(3))_(4)(NO_(3))_(2)+K_(4)[Fe(CN)_(6)] to Cu_(2)[Fe(CN)_(6)] darr` (chocolate brown). `Ba^(2+)+CuSO_(4) to BaSO_(4) darr ("white") +Cu^(2+)` |
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| 119. |
In which of the following pairs the precipitates are red and black coloured respectively and both precipitates are soluble in excess `Kl` solution?A. `Hgl_(2),Hg_(2)l_(2)`B. `Hgl_(2),Bil_(3)`C. `Cu_(2)l_(2),Agl`D. `Cdl_(2),Pbl_(2)` |
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Answer» Correct Answer - B `Hgl_(2)darr("red")+2l^(-)to[Hgl_(4)]^(2-)("soluble colourless complex"),Bil_(3)darr("black")+l^(-)to[Bil_(4)]^(-)`(soluble orange complex) |
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| 120. |
(i)A black coloured compound `(B)` is formed on passing `H_(2)S` through the solution of a compound `(A)` in `NH_(4)OH` (ii)`(B)` on treatment with `HCl` and potassium chlorate or aquaregia gives `(A)` (iii)`(A)` on treatment with `KCN` gives a buff/reddish-brown coloured precipitate which dissolves in excess of this reagent forming a compound `( C)`. (iv)The compound `( C)` is changed into a compound `(D)` when its aqueous solution is boiled in air. (v)The solution of `(A)` was treated with excess of `NaHCO_(3)` & then with bromine water. On cooling & shaking for some time, a green colour of compound `(E)` is formed.No change is observed on heating. Identify `(A)` to `(E)` and give chemical equations. |
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Answer» Correct Answer - (A)=`CoCl_(2)` , (B)=`CoS` , (C )=`K_(4)[Co(CN)_(6)]` , (D)=`K_(3)[Co(CN)_(6)]`, (E)=`Na_(3)[Co(CO_(3))_(3)]` (i)`Co_(2+) + S^(2-) overset (NH_(4)OH//NH_(4)Cl) to CoS darr` (black) (ii)`CoS darr + HNO_(3)+ 3HCl to Co^(2+) +S darr + NOCl uarr + 2Cl^(-) + 2H_(2)O` (iii)`Co^(2+) + 2CN^(-) to Co(CN)_(3) darr` (reddish-brown) `Co(CN)_(2) darr + 4CN^(-) to 4[Co(CN)_(6)]^(4-)`(brown solution) (iv)`4[Co(CN)_(6)]^(4-) + H_(2)O + O_(2) to 4[Co(CN)_(6)]^(3-)` (yellow solution)+`4OH^(-)` (v)`Co^(2+) + 6HCO_(3)^(-) to [Co(CO_(3))_(3)]^(4-) + 3H_(2)O + 3CO_(2)` `[Co(CO_(3))_(3)]^(4-) overset([O])to[Co(CO_(3))_(3)]^(3-)` (green solution) |
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| 121. |
A substance responds to the following test `:` `(a)` It gives a green precipitate with ammonia solution which dissolves in excess reagent forming deep blue solution. `(b)` it gives green precipitate with potassium cyanide solution which dissolves in excess reagent forming a yellow solution. `(c )` It gives green a reddish`-` brown`//` brown `-` borax bead test in the oxidising flame. The substance is `:`A. `Sr^(2+)` saltB. `Ni^(2+)` saltsC. `Mn^(2+)` saltsD. `Zn^(2+)` salts |
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Answer» Correct Answer - 2 `(a)Ni^(2+)+2NH_(3)+2H_(2)OrarrNi(OH)_(2) darr ("green")+2NH_(4)^(+)` `Ni(OH)_(2)darr+6NH_(3)rarr[Ni(NH_(3))_(6)]^(2+)("deep blue")+2OH^(-)` `(b)Ni^(2+)+2CN^(-)rarrNi(CN)_(2)darr("green")` `Ni(CN)_(2)+2CN^(-)rarr [Ni(CN)_(4)]^(2-)("yellow")` `(c )Ni(BO_(2))_(2)-` reddish brown or brown borax bead in oxidising flame. |
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| 122. |
Ammonium salts on heating with slaked lime liberates a colourless gas `(X)`. Identify the correct statement for gas `(X)` and ammonium salt.A. It turns red litmus blue and gives yellow ppt. with `Na_(3)[Co(NO_(2))_(6)]`B. It turns filter paper moistened with mercurous nitrate black and gives intense blue coloured solution with `CuSO_(4)(aq)`C. It when passed through Nessler reagent produces a brown colour ppt.D. All of these |
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Answer» Correct Answer - 4 `(1) NH_(3)` alkaline in nature turns and red litmus blue , `3NH_(4)Cl+Na_(3)[Co(NO_(2))_(2)]rarr(NH_(4))_(3)[Co(NO_(2))_(6)]darr("yellow")+3NaCl`. `(2) 2HgNO_(3)+2NH_(3)rarrubrace(Hg(NH_(2))NO_(3)+Hg)_("black")+NH_(4)NH_(3),CuSO_(4)+4NH_(3)rarr[Cu(nh_(3))_(4)]SO_(4)("intense blue ")` `(3)2K_(2)(HgI_(4))+NH_(3)+3KOHrarrHgOHgNH_(2)Idarr("brown")+7KI+2H_(2)O` |
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| 123. |
Which of the following cations does not import colour to the flame in flame test ?A. `Ba^(2+)`B. `Mg^(2+)`C. `Ca^(2+)`D. `Cu^(2+)` |
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Answer» Correct Answer - 2 Mg due to high ionisation energy does not import any colour to the flame in flame test. |
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| 124. |
Passing `H_(2)S` gas into a mixture of `Mn^(+2),Ni^(2+),Cu^(2+)` and `Hg^(2+)` ions in an acidified aqueous solution precipitatesA. CuS and HgSB. MnS and CuSC. MnS and NiSD. NiS and HgS |
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Answer» Correct Answer - A `Cu^(+2)` and `Hg^(+2)` are II group basic radicals with `H_(2)S` in presence of acid (dil. HCl) CuS(black),HgS(black)ppt are obtain |
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| 125. |
A metal X on heating with nitrogen gas gives Y.Y on treatment with `H_(2)O` gives a colourless gas which on passing through `CuSO_(4)` gives blue solution then Y isA. `MgO`B. `Mg_(3)N_(2)`C. `MgSO_(4)`D. `CaO` |
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Answer» Correct Answer - 2 `3Mg+N_(2)rarrMg_(3)N_(2)` `Mg_(3)N_(2)+6H_(2)O rarr 3Mg(OH)_(2)+2NH_(3)` `CuSO_(4)+4NH_(3)rarr underset(("deep blue"))([Cu(NH_(3))_(4)]SO_(4))` |
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| 126. |
Which of the following anions gives blood red colour with neutral `FeCl_(3)` solution ?A. AcetateB. CarbonateC. ChlorideD. Bromide |
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Answer» Correct Answer - 1 Acetate with neutral `FeCl_(3)` solution gives blood red colour. |
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| 127. |
Oxalate `+MnO_(2)+"dil."H_(2)SO_(4)rarr ` Gas. The gas evolved isA. `CO_(2)`B. COC. `SO_(2)`D. `O_(2)` |
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Answer» Correct Answer - 1 `CO_(2)` gas is evolved. |
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| 128. |
`K_(4)[Fe(CN)_(6)]` is not used for the detection ofA. `Fe^(2+)` ionsB. `Zn^(2+)` ionsC. `Cu^(2+)` ionsD. `Fe^(3+)` ions |
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Answer» Correct Answer - 1 `Cu^(+2)+[Fe(CN)_(6)]^(4-)rarrunderset("reddish brown")(Cu_(2)[Fe(CN)_(6)]darr)` `4Fe^(3+)+3[Fe(CN)_(6)]^(4-)rarr underset("blue")(Fe_(4)[Fe(CN)_(6)]_(3)darr)` `Zn^(2+)+[Fe(CN)_(6)]^(4-)rarr underset("bluish white ppt")(Zn_(2)[Fe(CN)_(6)darr)` |
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| 129. |
A chemist opened a cupboard to find four bottles containing water solutions, each of twhich had lost its lable. Bottles 1,2,3 contained colourless solutions , while bottle 4 contained coloured solution. They were, Copper (II) sulphate, Hydrochloric acid. Lead nitrate, Sodium carbonate. By mixing samples of the contents of the bottles, in pairs. The chemist made the following observations, Bottle `1+` Bottle 2 white precipitate Bottle `1=` Bottle 3 white precipitate Bottle `1+` Bottle 4 white precipitate Bottle `2+` Bottle 3 colour less gas evolved Bottle `2+` Bottle 4 no visible reaction Bottle `3+` Bottle 4 blue precipitate. Bottle 3 contains `:`A. Copper (II) sulphateB. hydrochloric acidC. lead nitrateD. sodium carbonate |
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Answer» Correct Answer - 4 Bottle `2+` Bottle 3 `rarr ` Colour less `(CO_(2))` `Na_(2)CO_(3)+` acid `rarr Co_(2)(` Colour lessgas ) Bottle `3+` Bottle `4 rarr ` Blue precipitate confirms `Cu^(+2)` in either bottle. Hence Bottle `3 rarr Na_(2)CO_(3),` Bottle `4 rarr CuSO_(4)` Bottle `2 rarr HCl, ` So Bottle `1 rarr PbNO_(3)` |
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| 130. |
A chemist opened a cupboard to find four bottles containing water solutions, each of twhich had lost its lable. Bottles 1,2,3 contained colourless solutions , while bottle 4 contained coloured solution. They were, Copper (II) sulphate, Hydrochloric acid. Lead nitrate, Sodium carbonate. By mixing samples of the contents of the bottles, in pairs. The chemist made the following observations, Bottle `1+` Bottle 2 white precipitate Bottle `1=` Bottle 3 white precipitate Bottle `1+` Bottle 4 white precipitate Bottle `2+` Bottle 3 colour less gas evolved Bottle `2+` Bottle 4 no visible reaction Bottle `3+` Bottle 4 blue precipitate. Which of the bottle will give distinctive blue colour with `NH_(3)` ?A. Bottle 1B. Bottle 2C. Bottle 3D. Bottle 4 |
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Answer» Correct Answer - 4 `CuSO_(4)+4Nh_(3)rarr[Cu(NH_(3))_(4)]SO_(4)` |
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| 131. |
A chemist opened a cupboard to find four bottles containing water solutions, each of twhich had lost its lable. Bottles 1,2,3 contained colourless solutions , while bottle 4 contained coloured solution. They were, Copper (II) sulphate, Hydrochloric acid. Lead nitrate, Sodium carbonate. By mixing samples of the contents of the bottles, in pairs. The chemist made the following observations, Bottle `1+` Bottle 2 white precipitate Bottle `1=` Bottle 3 white precipitate Bottle `1+` Bottle 4 white precipitate Bottle `2+` Bottle 3 colour less gas evolved Bottle `2+` Bottle 4 no visible reaction Bottle `3+` Bottle 4 blue precipitate. When bottle 1 is mixed with bottle 4, white precipitate is observed, which is `:`A. `PbSO_(4)`B. `PbCO_(3)`C. `PbCl_(2)`D. `Pb(NO_(3))_(2)` |
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Answer» Correct Answer - 1 `Pb(NO_(3))_(2)+CuSO_(4)rarrCu(NO_(3))_(2)+PbSO_(4)` |
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| 132. |
Which one has the minimum solubility product ?A. `AgCl`B. `AlCl_(3)`C. `BaCl_(2)`D. `NH_(4)Cl` |
| Answer» Correct Answer - 1 | |
| 133. |
Disodium hydrogen phosphate is used to testA. `Mg^(2+)`B. `Ca^(+2)`C. `Na^(+)`D. `Zn^(2+)` |
| Answer» Correct Answer - 1 | |
| 134. |
Which one of the following can be used in place of `NH_(4)Cl` for the identification of the third group radicals ?A. `NH_(4)NO_(3)`B. `(NH_(4))_(2)SO_(4)`C. `(NH_(4))_(2)CO_(3)`D. `NaCl` |
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Answer» Correct Answer - A As it provides `NH_(4)^(+)` ions which suppresses the ionisation of `NH_(4)OH` so that only the group `3^(rd)` cations are precipitated as hydroxides because of their low solubility products and `NO_(3)^(-)` ions do not produc precipitate with the cations of `IV^(th),V^(th)` and `VI^(th)` groups. |
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| 135. |
In the precipitation of the iron group in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide toA. decrease concentration of `OH^(-)` ionsB. prevent interference by phosphate ionsC. increase concentration of `Cl^(-)` ionsD. increase concentration of `NH_(4)^(+)` ions |
| Answer» Correct Answer - A | |
| 136. |
A reddish - pink substance on heating gives off a vapour which condenses on the sides of test cube and the substance turns blue. If on cooling water is added to the residue it turns to its original colour. The substance isA. Iodine crystalB. Copper sulphate crystalsC. Cobalt chloride crystalsD. Zinc oxide |
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Answer» Correct Answer - C It is property of `CoCl_(2)` |
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| 137. |
When a mixture containing phosphate is heated with conc. `HNO_(3)` and ammonium molybdated solution, a canary yellow precipitate is formed . The formula of the yellow precipitate isA. `(NH_(4))_(3)PO_(4)`B. `(NH_(4))_(3)PO_(4).12MoO_(4)`C. `(NH_(4))_(3)PO_(4).12MoO_(3)`D. `(NH_(4))_(3)PO_(4).(NH_(4))_(2)MoO_(4)` |
| Answer» Correct Answer - 3 | |
| 138. |
Ammonia/ammonium ion gives yellow precipitate with:A. `H_(2)PtCl_(6)`B. `HgCl_(2)`C. `Na_(3)[Co(NO_(2))_(6)]`D. (A) and ( C) both |
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Answer» Correct Answer - D `NH_(4)^(+)+[PtCl_(6)]^(2-)to(NH_(4))_(2)[PtCl_(6)]darr` (yellow). `[Co(NO_(2))_(6)]^(3-)+3NH_(4)^(+)to(NH_(4))_(3)[Co(NO_(2))_(6)]darr` (yellow) |
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| 139. |
There are four test tubes containing dilute `HCl,BaCl_(2),CdCl_(2)` and `KNO_(3)` soluitons.Which of the following reagents with help in the identification of `BaCl_(2)`?A. `NaOH`B. `K_(2)CrO_(4)`C. `AgNO_(3)`D. both (B) and ( C) |
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Answer» Correct Answer - B `Ba^(2+)+CrO_(4)^(2-)toBaCrO_(4)darr("yellow"),Ag^(+)+Cl^(-)toAgCldarr` (white) |
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| 140. |
A solution of colourless salt H on boiling with axcess `NaOH` produces a non-flammable gas. The gas evolution ceases after sometime. Upon addition of Zn dust to the same solution, the gas evolution restarts. The colourless salt(s) H is (are)A. `NH_(4)NO_(3)`B. `NH_(4)NO_(2)`C. `NH_(4)Cl`D. `(NH_(4))_(2)SO_(4)` |
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Answer» Correct Answer - A::B |
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| 141. |
The mixture of 6 mole lithium, 1 mol sodium and 3 moles magnesium on reaction with excess nitrogen gas at high temperature gives metal nitrides. Total number of consumed mole of nitrogen gas is ? |
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Answer» Correct Answer - 2 `Li+N_(2)rarrLi_(3)N` `Na+N_(2)rarr` No reaction `Mg+N_(2)rarr Mg_(3) N_(2)` On the basis of mole concept. |
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| 142. |
(A) `:` `PbCl_(2)` and `HgCl_(2)` precipitates can be separated by hot water. `(R ) :` Aqueous solution of `PbCl_(2)` give yellow precipitate with `K_(2)CrO_(4)` solution. |
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Answer» Correct Answer - 2 `Pb^(+2)` is present if the precipitate disosolves in hot water. `Hg_(2)^(2+)` is present if the precipitate does not dissolve in hot water. |
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| 143. |
Statement 1 `: PbCl_(2)` and `Hg_(2)Cl_(2)`precipitates can be separated by hot water because. Statement 2 `: Hg_(2)Cl_(2)` is backend by aq. `NH_(3)` |
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Answer» Correct Answer - B `PbCl_(2)` gets soluble in hot water. |
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| 144. |
Which one of the following statement is correct ?A. From a mixed precipitate of `AgCl` and `AgI` , ammonia solution dissolves only `AgCl` completely.B. `I^(-)`ions gives red precipitate with `Hg_(2)^(2+)` ions solutionC. On boiling a solution having `Ca^(2+),K` and `HCO_(3)` ions we get white precipitate.D. `(1)` and `(3)` both |
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Answer» Correct Answer - 4 `(1) AgCl` is soluble while Agl is partialy solubel in concentrated ammonia solution. `K^(+)+Ca^(2+)+HCO_(3)^(-)overset(Delta)rarr CaCO_(2)darr+CO_(2) uarr+H_(2)O+K_(2)CO_(3)` |
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| 145. |
Which of the following statement (s) is (are) correct when a mixture of `NaCl` and `K_(2)Cr_(2)O_(7)` is gently warmed with conc. `H_(2)SO_(4)` ?A. A deep red vapour is evolvedB. The vapour when passed into NaOH solution gives a yellow solution of `Na_(2)CrO_(4)`C. `Cr_(2)O_(7)^(-2)` is reduced to `Cr^(+3)`D. Chromyl chloride is formed |
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Answer» Correct Answer - A,B,D Chromylchloride test `4NaCl+K__(2)Cr_(2)O_(7)+3H_(2)SO_(4)overset("heat")(rarr)underset("chromyl chloride (orange red)")(K_(2)SO_(4)+2Na_(2)SO_(4)+2CrO_(2)Cl_(2)+3H_(2)O)` `4NaOH+CrO_(2)Cl_(2)rarr underset("sod. Chromate (yellow)")(2NaCl+Na_(2)CrO_(4)+2H_(2)O)` `Na_(2)CrO_(4)+(CH_(3)COO)_(2)Pbrarrunderset(("Lead chromate yellow ppt."))(2Ch_(3)COONa+PbCrO_(4)darr)` |
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| 146. |
When disodium hydrogenphosphate is added to the a salt solution of `Mg^(2+)` in the presence of `NH_(4)OH`, it givesA. A white ppt.B. A pink ppt.C. `Mg(NH_(4))PO_(4)`D. `Mg(NH_(4))HPO_(4)` |
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Answer» Correct Answer - A,C `Mg^(2+)` from white coloured ppt. of `Mg(NH_(4))PO_(4)`. |
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| 147. |
What products are formed ? When : (i)Disodium hydrogen phosphate is added to magnesium sulphate in presence of ammonium chloride and aqueous ammonia. (ii)A solution containing `Zn^(2+)` ions is poured in an aqueous ammonia. (iii)`Bi(NO_(3))_(3)` solution is mixed with `KI` and then resulting precipitate is heated with water. (iv)Disodium hydrogen phosphate is boiled with concentrated `HNO_(3)` and ammonium molybdate reagent. |
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Answer» Correct Answer - (i)`Mg^(2+) +NH_(3) +HPO_(4)^(2-) to Mg(NH_(4))PO_(4) darr` (white) (ii)`Zn^(2+) + 2NH_(4)OH to Zn(OH)_(2) darr ("white") +2NH_(4)^(+)` `Zn(OH)_(2)+4NH_(4)OH to [Zn(NH_(3))_(4)](OH)_(2) +4H_(2)O` (iii)`Bi^(3+) + 3I^(-) to BiI_(3) darr` (black). `BiI_(3) darr + H_(2)O overset(Delta)to BiOI darr` (orange)`+2H^(+) +2I^(-)` (iv)`Na_(2)HPO_(4) +12 (NH_(4))_(2)MoO_(4) +23HNO_(3) to underset(("canary yellow"))((NH_(4))_(3)PMo_(12))O_(40) darr + 2NaNO_(3) +21NH_(4)NO_(3) +12H_(2)O` |
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| 148. |
Disodium hydrogen phosphate is used to testA. `Mg^(2+)`B. `Na^(+)`C. `Ca^(2+)`D. All |
| Answer» Correct Answer - 1 | |
| 149. |
Which of the following hydroxide is soluble in excess of NaOHA. `Fe(OH)_(3)`B. `Cr(OH)_(3)`C. `Al(OH)_(3)`D. All |
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Answer» Correct Answer - 2,3 `Al(OH)_(3)+NaOH rarr underset(("soluble"))(NaAlO_(2))+2H_(2)O` |
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| 150. |
Acidic `K_(2)Cr_(2)O_(7)` reacts with `H_(2)S` to produceA. `Cr^(+6)`B. `Cr^(+4)`C. SD. `SO_(2)` |
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Answer» Correct Answer - C `Cr_(2)O_(7)^(2-)+3H_(2)S+8H^(+)rarr2Cr^(3+)+7H_(2)O+3S` |
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