Over 100 Short Q&A for Salt Analysis

 over 100 short question-and-answer pairs covering the essential concepts, procedures, and observations for identifying acidic (anions) and basic (cations) radicals:

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Over 100 Short Q&A for Salt Analysis (Class 12 NCERT Lab Manual)

Part 1: Basic Concepts and Preliminary Tests

Q. No.	Question	Answer
1	What are the two main parts of an inorganic salt analyzed in the lab?	Acidic Radical (Anion) and Basic Radical (Cation).
2	Why are preliminary tests important in salt analysis?	They provide clues about the presence or absence of certain radicals, saving time.
3	What is the purpose of preparing a Sodium Carbonate Extract (S.C.E.)?	To convert insoluble salts (like BaSO4​) into soluble sodium salts for anion testing.
4	Why is Na2​CO3​ used for preparing the extract?	Na salts are almost all soluble in water.
5	What happens to the cation during the preparation of S.C.E.?	It forms a precipitate (e.g., BaCO3​) which is removed by filtration.
6	What color is imparted to the flame by Na+?	Golden yellow.
7	What color is imparted to the flame by Ca2+?	Brick red.
8	What color is imparted to the flame by Ba2+?	Apple green.
9	What is the observation when a salt is heated in a dry test tube and H2​O droplets condense?	Suggests the salt is a hydrated salt.
10	What does the evolution of brown fumes upon heating suggest?	Presence of Nitrate (NO3−​) or Bromide (Br−) ions.

Part 2: Anion Analysis (Acidic Radicals) - Group 1 (Dil. H2SO4)

Q. No.	Question	Answer
11	What is the common group reagent for Group 1 anions?	Dilute Sulphuric Acid (Dil. H2​SO4​).
12	Name the four common anions belonging to Group 1.	CO32−​ (Carbonate), S2− (Sulphide), SO32−​ (Sulphite), NO2−​ (Nitrite).
13	What is the gas evolved when a carbonate salt reacts with dil. H2​SO4​?	CO2​ (Carbon dioxide).
14	How is the CO2​ gas confirmed?	It turns lime water milky (Ca(OH)2​) due to the formation of CaCO3​.
15	What is the gas evolved when a sulphide salt reacts with dil. H2​SO4​?	H2​S (Hydrogen sulphide).
16	How is the H2​S gas confirmed?	It turns lead acetate paper black (PbS) or sodium nitroprusside solution purple.
17	What is the gas evolved when a sulphite salt reacts with dil. H2​SO4​?	SO2​ (Sulphur dioxide).
18	How is the SO2​ gas confirmed?	It turns acidified KMnO4​ solution colorless (decolorization).
19	What is the gas evolved when a nitrite salt reacts with dil. H2​SO4​?	Brown fumes of NO2​ (Nitric dioxide) upon heating/exposure to air.
20	What is the final confirmatory test for S2−?	Sodium Nitroprusside Test (Purple/Violet color).

Part 3: Anion Analysis - Group 2 (Conc. H2SO4)

Q. No.	Question	Answer
21	What is the common group reagent for Group 2 anions?	Concentrated Sulphuric Acid (Conc. H2​SO4​).
22	Name the three common anions belonging to Group 2.	Cl− (Chloride), Br− (Bromide), I− (Iodide).
23	What gas is evolved when Cl− reacts with conc. H2​SO4​?	HCl (Hydrogen chloride - white fumes with NH3​).
24	What is the confirmatory test for Cl− involving K2​Cr2​O7​?	Chromyl Chloride Test (Red-brown vapors of CrO2​Cl2​ confirmed by yellow Na2​CrO4​).
25	What is the observation when Br− reacts with conc. H2​SO4​ and MnO2​?	Reddish-brown vapors of Br2​ (Bromine).
26	What is the observation when I− reacts with conc. H2​SO4​ and MnO2​?	Violet vapors of I2​ (Iodine).
27	What is the common confirmatory test for all halides (Cl−,Br−,I−) using S.C.E.?	Silver Nitrate (AgNO3​) Test (formation of AgX precipitates).
28	What is the color and solubility in NH4​OH of the AgCl precipitate?	White, soluble in dilute NH4​OH.
29	What is the color and solubility in NH4​OH of the AgBr precipitate?	Pale yellow, sparingly soluble in dilute NH4​OH.
30	What is the color and solubility in NH4​OH of the AgI precipitate?	Yellow, insoluble in NH4​OH.
31	What is the specific test for Br− and I− using CCl4​/CHCl3​?	Layer Test (color of Br2​ or I2​ extracted into the organic layer).
32	What color does the CCl4​ layer turn for Br−?	Brown/Orange.
33	What color does the CCl4​ layer turn for I−?	Violet.

Part 4: Anion Analysis - Group 3 (NO^3-,SO4^2-, PO4^3-,C2O4^2-

Q. No.	Question	Answer
34	Which three anions are tested using S.C.E. because they do not react with H2​SO4​?	NO3−​ (Nitrate), SO42−​ (Sulphate), PO43−​ (Phosphate).
35	What is the name of the standard confirmatory test for NO3−​?	Ring Test (Brown Ring Test).
36	What reagents are required for the Ring Test?	Ferrous Sulphate (FeSO4​) solution and Concentrated H2​SO4​ (added carefully along the sides).
37	What is the compound responsible for the brown ring in the Ring Test?	Nitroso Ferrous Sulphate ([Fe(H2​O)5​NO]SO4​).
38	What is the confirmatory test for SO42−​ using S.C.E.?	Barium Chloride (BaCl2​) Test.
39	What is the observation in the BaCl2​ test for SO42−​?	Thick white precipitate of BaSO4​ (insoluble in conc. HCl).
40	What is the confirmatory test for PO43−​?	Ammonium Molybdate Test.
41	What is the observation in the Ammonium Molybdate Test for PO43−​?	Canary yellow precipitate upon heating.
42	What is the confirmatory test for Oxalate (C2​O42−​) using S.C.E.?	CaCl2​ Test (White precipitate of CaC2​O4​ soluble in dil. HCl).
43	What is the final confirmatory test for C2​O42−​?	KMnO4​ Test (Oxalate reduces hot KMnO4​ solution).
44	Which anion is confirmed by heating the salt with conc. H2​SO4​ and R-OH (alcohol)?	Acetate (CH3​COO−) (Smell of fruity ester).
45	What is the common name for the test in the previous question?	Ester Test.

Part 5: Cation Analysis (Basic Radicals) - Groups 0 to 3

Q. No.	Question	Answer
46	What is the group reagent for Group 0 cations?	NaOH solution.
47	Name the only cation in Group 0.	NH4+​ (Ammonium ion).
48	What is the gas evolved when NH4+​ salt is heated with NaOH?	NH3​ (Ammonia gas).
49	How is NH3​ gas confirmed?	It turns Nessler's Reagent brown/reddish-brown.
50	What is the group reagent for Group 1 cations?	Dilute HCl.
51	Name the common cations belonging to Group 1.	Pb2+,Ag+,Hg22+​ (Precipitate as chlorides).
52	What is the group reagent for Group 2 cations?	H2​S gas in the presence of dil. HCl.
53	Name the common cations belonging to Group 2 (Cu2+,Cd2+,As3+,Pb2+).	They precipitate as Sulphides (insoluble in cold dilute acids).
54	What is the group reagent for Group 3 cations?	NH4​OH in the presence of NH4​Cl.
55	Name the common cations belonging to Group 3.	Al3+,Fe3+,Cr3+ (Precipitate as Hydroxides).
56	Why is NH4​Cl added before NH4​OH in Group 3 analysis?	To suppress the ionization of NH4​OH (Common Ion Effect), preventing precipitation of higher groups (Mg2+,Ba2+).
57	What is the color of the Al3+ precipitate?	Gelatinous white precipitate (Al(OH)3​).
58	What is the color of the Fe3+ precipitate?	Reddish-brown precipitate (Fe(OH)3​).
59	What is the color of the Cr3+ precipitate?	Green precipitate (Cr(OH)3​).
60	What is the confirmatory test for Fe3+ using K4​[Fe(CN)6​]?	Prussian Blue color/precipitate.
61	What is the confirmatory test for Al3+ using NaOH?	Al(OH)3​ is soluble in excess NaOH (amphoteric nature).
62	What is the final confirmatory test for Cr3+?	Chromyl Chloride Test (after oxidation) or Lead Acetate Test (Yellow precipitate of PbCrO4​).

Part 6: Cation Analysis - Groups 4 to 6

Q. No.	Question	Answer
63	What is the group reagent for Group 4 cations?	H2​S gas in the presence of NH4​OH/NH4​Cl buffer.
64	Name the common cations belonging to Group 4.	Zn2+,Mn2+,Ni2+,Co2+ (Precipitate as Sulphides).
65	What is the color of the Zn2+ precipitate?	Dirty white precipitate (ZnS).
66	What is the color of the Mn2+ precipitate?	Buff/Flesh-colored precipitate (MnS).
67	What is the confirmatory test for Ni2+?	Dimethylglyoxime (DMG) Test (Rose-red precipitate).
68	What is the confirmatory test for Co2+?	Ammonium Thiocyanate Test (Blue color in organic layer).
69	What is the group reagent for Group 5 cations?	Ammonium Carbonate ((NH4​)2​CO3​) in the presence of NH4​OH/NH4​Cl.
70	Name the common cations belonging to Group 5.	Ba2+,Sr2+,Ca2+ (Precipitate as Carbonates).
71	How are the Group 5 cations distinguished?	By Flame Test (distinct colors).
72	What is the group reagent for Group 6 cations?	No specific reagent; they are tested individually.
73	Name the common cation belonging to Group 6.	Mg2+ (Magnesium ion).
74	What is the confirmatory test for Mg2+?	Disodium Hydrogen Phosphate Test (Na2​HPO4​) (White precipitate of MgNH4​PO4​).
75	What is the color of the precipitate formed by Ba2+,Sr2+,Ca2+ with (NH4​)2​CO3​?	White.

Part 7: Conceptual and Mixed Problems

Q. No.	Question	Answer
76	What is the key principle behind separating cation groups?	The difference in the solubility products (Ksp​) of their salts.
77	Why is the concentration of S2− controlled by dil. HCl in Group 2 analysis?	To selectively precipitate only Group 2 sulphides (Ksp​ is low).
78	Why does Pb2+ belong to both Group 1 and Group 2?	PbCl2​ is soluble in hot water, so some Pb2+ escapes to Group 2 where it precipitates as PbS.
79	What is the main reason for the yellow color of the K2​CrO4​ solution in the Chromyl Chloride Test?	CrO42−​ (Chromate ion).
80	What happens if NH4​Cl is not added to the Group 3 test?	Mg(OH)2​ (from Group 6) may also precipitate prematurely.
81	What is the effect of excess NH4​OH on the Cu2+ precipitate in Group 2?	The CuS precipitate is insoluble, but Cu2+ forms a deep blue solution ([Cu(NH3​)4​]2+) on treatment with NH4​OH after separation.
82	What happens to the BaCO3​ precipitate when acetic acid is added?	It dissolves (BaCO3​ reacts with the weak acid).
83	What is the confirmatory test for Cu2+ using K4​[Fe(CN)6​]?	Chocolate brown precipitate (Cu2​[Fe(CN)6​]).
84	Why are Group 5 carbonates soluble in acetic acid?	The carbonates are salts of a strong base and a weak acid, and are easily protonated.
85	Why is the Ring Test always performed with freshly prepared FeSO4​?	Fe2+ is easily oxidized to Fe3+ upon standing, which interferes with the test.
86	What is the general procedure for testing a mixture of two basic radicals?	The radicals are separated sequentially by precipitation using group reagents.
87	What is the general procedure for testing a mixture of two acidic radicals?	Individual tests are performed, as separation is generally difficult.
88	What is the color imparted to the flame by K+?	Lilac/Violet.
89	What is the color imparted to the flame by Cu2+?	Bluish green.
90	What is the significance of the solubility of a salt in water?	Helps differentiate between AgCl and PbCl2​ (Group 1); PbCl2​ is soluble in hot water.
91	What is the reagent used to confirm $\text{Sulphite ($\text{SO}_3^{2-})$}$ by its reaction with BaCl2​?	White precipitate of BaSO3​, which dissolves in dil. HCl.
92	What are the necessary precautions when conducting the Ring Test?	Conc. H2​SO4​ must be added slowly along the wall of the test tube.
93	What is the white ppt formed in the confirmatory test for Mg2+?	Magnesium Ammonium Phosphate (MgNH4​PO4​).
94	Which Group 2 sulphide is confirmed by treating its yellow ppt with Yellow Ammonium Sulphide?	Arsenic Sulphide (As2​S3​).
95	What is the formula of the reagent used for the DMG test?	Dimethylglyoxime (C4​H8​N2​O2​).
96	Name the cation that gives a carmine red color in the flame test.	Sr2+ (Strontium ion).
97	What is the color change when FeSO4​ solution is added to the NO2−​ test solution?	Dark brown/black color (immediate reaction).
98	Why are Group 5 salts precipitated as carbonates and not as sulphates?	Sulphates of Ba,Sr,Ca have very low Ksp​ and would precipitate Pb2+,Hg2+ etc., from previous groups.
99	What is the purpose of performing the Microcosmic Salt Bead Test (or Borax Bead Test)?	A preliminary test for colored basic radicals (Ni2+,Co2+,Cr3+).
100	Why is the Group 6 cation analysis often done only after ensuring all previous groups are absent?	Group 6 contains Mg2+, which has a high solubility product and can be mistaken for other groups if reagents are not carefully controlled.
101	What color is obtained when MnO2​ is heated with conc. H2​SO4​?	Cl2​ gas (Greenish-yellow gas).
102	What is the primary function of the Charcoal Cavity Test?	To detect the presence of easily reducible basic radicals (Pb2+,Ag+,Cu2+).
103	What is the final step in confirming Zn2+ after forming ZnS precipitate?	ZnS precipitate is dissolved in dil. HCl and confirmed by K4​[Fe(CN)6​] (White or Bluish-White precipitate).
104	What are the possible interfering anions in Group 3 analysis?	Oxalate (C2​O42−​) and Phosphate (PO43−​), which can precipitate Ba,Sr,Ca etc. prematurely.
105	How are interfering anions like Phosphate removed?	By adding conc. HNO3​ and heating with (NH4​)2​MoO4​ or forming AlPO4​ precipitate.
106	Why should the original salt solution always be used for confirmatory tests whenever possible?	To avoid contamination from group reagents.