Salt Analysis and Qualitative Analysis Exercise # 5

SALT ANALYSIS AND QUALITATIVE ANALYSIS Exercise # 5 1. [Previous Year Questions] [AIEEE/JEE-MAIN] An alkali is titrated against an acid with Methyl organe as indicator, which of the following is a correct combination? Base Acid End point (1) Strong Strong Pinkish red to yellow (2) Weak Strong Yellow to Pinkish red (3) Strong Strong Pink to colourless (4) Weak Strong Colourless to Pink Part # II 1. Part # I [Previous Year Questions][IIT-JEE ADVANCED] A sodium salt on treatment with MgCl2 gives white precipitate only on heating. The anion of the sodium salt is: (A) HCO3– (B) CO32– (C) NO3– (D) SO42– 2. A metal nitrate reacts with KI to give a black precipitate which on addition of excess of KI is converted into orange colour solution. The cation of the metal nitrate is : (A) Hg2+ (B) Bi3+ (C) Pb2+ (D) Cu+ 3. A white precipitate is obtained when a solution is diluted with H2O and boiled. On addition of excess NH4Cl/NH4OH, the volume of precipitate decreases leaving behind a white gelatinous precipitate. Identify the precipitate which dissolves in ammonia solution or NH4Cl. (A) Al(OH)3 (B) Zn(OH)2 (C) Mg(OH)2 (D) Ca(OH)2 4. In blue solution of copper sulphate excess of KCN is added then solution becomes colourless due to the formation of (A) [Cu(CN)4]2– (C) Cu(CN)2 5. 6. 7. (B) Cu2+ get reduced to form [Cu(CN)4]3– (D) CuCN MgSO4 + NH4OH + Na2HPO4  white crystalline precipitate. The formula of crystalline precipitate is : (A) MgCl2. MgSO4 (B) MgSO4 (C) Mg(NH4)PO4 (D) Mg(PO4)2 A solution of a metal ion when treated with K gives a red precipitate which dissolves in excess K to give a colourless solution. Moreover, the solution of metal ion on treatment with a solution of cobalt(II) thiocyanate gives rise to a deep blue crystalline precipitate. The metal ion is : (A) Pb2+ (B) Hg2+ (C) Cu2+ (D) Co2+ A solution of colourless salt H on boiling with excess NaOH produces a nonflammable gas. The gas evolution ceases after some time. Upon addition of Zn dust to the same solution, the gas evolution restarts. The colourless salt(s) H is (are) : (A) NH4NO3 (B) NH4NO2 (C) NH4Cl (D) (NH4)2SO4 Paragraph for Question Nos. 8 to 10 p-Amino-N, N-dimethylaniline is added to a strongly acidic solution of X. The resulting solution is treated with a few drops of aqueous solution of Y to yield blue coloration due to the formation of methylene blue. Treatment of the aqueous solution of Y with the reagent potassium hexacyanoferrate(II) leads to the formation of an intense blue precipitate. The precipitate dissolves on excess addition of the reagent. Similarly, treatment of the solution of Y with the solution of potassium hexacyanoferrate(III) leads to a brown coloration due to the formation of Z. 8. 9. 10. The compound X is : (A) NaNO3 (B) NaCl (C) Na2SO4 (D) Na2S The compound Y is : (A) MgCl2 (B) FeCl2 (C) FeCl3 (D) ZnCl2 The compound Z is : (A) Mg2[Fe(CN)6] (C) Fe4[Fe(CN)6]3 (B) Fe[Fe(CN)6] (D) K2Zn3[Fe(CN)6]2 Paragraph for Question Nos. 11 to 13 When a metal rod M is dipped into an aqueous colourless concentrated solution of compound N the solution turns light blue. Addition of aqueous NaCl to the blue solution gives a white precipitate O. Addition of aqueous NH 3 dissolves O and gives an intense blue solution. 11. 12. 13. 14. The metal rod M is : (A) Fe (B) Cu (C) Ni (D) Co The compound N is : (A) AgNO3 (B) Zn(NO3)2 (C) Al(NO3)3 (D) Pb(NO3)2 The final solution contains (A) [Pb(NH3)4]2+ and [CoCl4]2– (C) [Ag(NH3)2]+ and [Cu(NH3)4]2+ Passing H2S gas into a mixture of Mn2+, Ni2+, Cu2+ and Hg2+ ions in an acidified aqueous solution precipitates: (A) CuS and HgS 15. 16. (B) [Al(NH3)4]3+ and [Cu(NH3)4]2+ (D) [Ag(NH3)2]+ and [Ni(NH3)6]2+ (B) MnS and CuS (C) MnS and NiS The equilibrium 2CuI Cu0 + CuII in aqueous medium at 25° C shifts towards the left in the presence of : (A) NO3– (B) Cl– (C) SCN– For the given aqueous reaction which of the statement(s) is (are) true ? (A) The first reaction is a redox reaction (B) White precipitate is Zn3[Fe(CN)6]2 (C) Addition of filtrate to starch solution gives blue colour. (D) White precipitate is soluble in NaOH solution (D) NiS and HgS (D) CN– SALT ANALYSIS AND QUALITATIVE ANALYSIS 17. Concentrated nitric acid, upon long standing, turns yellow-brown due to the formation of : (A) NO 18. (B) NO2 (C) N2O (D) N2O4 Upon treatment with ammoniacal H2S, the metal ion that precipitates as a sulfide is : (A) Fe(III) (B) Al (III) (C) Mg(II) (D) Zn(II) Paragraph for Question 19 and 20 19. 20. An aqueous solution of a mixture of two inorganic salts, when treated with dilute HCl, gave a precipitate (P) and a filtrate (Q). The precipitate P was found to dissolve in hot water. The filtrate (Q) remained unchanged, when treated with H2S in a dilute mineral acid medium. However, it gave a precipitate (R) with H2S in an ammoniacal medium. The precipitate R gave a coloured solution (S), when treated with H2O2 in an aqueous NaOH medium. The precipitate P contains (A) Pb2+ (B) Hg22+ (C) Ag+ (D) Hg2+ The coloured solution S contains (A) Fe2(SO4)3 (C) ZnSO4 (B) CuSO4 (D) Na2CrO4 21. In neutral or faintly alkaline solution, 8 moles of permanganate anion quantitatively oxidize thiosulphate anions to produce X moles of a sulphur containing product. The magnitude of X is 22. The correct option(s) to distinguish nitrate salts of Mn2+ and Cu2+ taken separately is (are) (A) Mn2+ show the characteristic green colour in the flame test. (B) Only Cu2+ show the formation of precipitate by passing H2S in acidic medium (C) Only Mn2+ show the formation of precipitate by passing H2S in faintly basic medium (D) Cu2+/Cu has higher reduction potential than Mn2+ / Mn (measured under similar conditions) EXERCISE - 5 : PART # I 1. 2 PART # II 1. A 2. B 3. B 4. B 10. B 11. B 12. A 13. C 19. A 20. D 21 6 22 B, D 5. C 14. A 6. B 15. B,C,D 7. A,B 16. A,C,D 8. D 17. B 9. C 18. D