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Precipitation reactions and confirmatory tests

35 questions on Precipitation reactions and confirmatory tests from the Qualitative Analysis: Anions chapter: 6 NEET level, 13 JEE Main, 16 JEE Advanced. Each one opens with its answer and solution.

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Which gas, evolved on treating a salt with dilute acid, turns filter paper moistened with lead acetate black? NEET level
Which of the following precipitates dissolves readily in dilute aqueous ammonia? NEET level
A salt on warming with dilute H2SO4 gives brown fumes, and a filter paper dipped in starch-iodide solution turns blue in these fumes. The anion is NEET level
A yellow precipitate formed on adding Pb(NO3)2 to a colourless solution dissolves on boiling, and golden-yellow spangles separate on cooling. The precipitate is JEE Main level
Assertion (A): Lime water alone cannot distinguish a carbonate from a sulphite when the salt is treated with dilute acid. Reason (R): Both CO2 and SO2 turn lime... JEE Main level
Silver nitrate solution is added dropwise to aqueous sodium thiosulphate. The precipitate changes from white to yellow to brown and finally to black. The final ... JEE Main level
Match Column I (anion) with Column II (observation with the stated reagent). Column I: P. S^2- with sodium nitroprusside; Q. NO2^- with FeSO4 and dilute acetic ... JEE Main level
Which of the following arranges the silver halides in decreasing order of solubility in aqueous ammonia (of the same concentration)? JEE Main level
Which of the following precipitates are yellow in colour? One or more options may be correct. JEE Main level
A white precipitate is formed on adding CaCl2 solution to a salt solution. It does not dissolve in dilute acetic acid but dissolves in dilute HCl, and the salt ... JEE Main level
A sodium salt gives no precipitate with MgSO4 solution in the cold, but a white precipitate (assume MgCO3) and a colourless gas appear on boiling. A 0.84 g samp... JEE Advanced level
A solid sodium salt on treatment with dilute H2SO4 evolves a colourless gas with a pungent smell which turns acidified K2Cr2O7 paper green and leaves the soluti... JEE Advanced level
Which statements about the thiosulphate ion are correct? One or more options may be correct. JEE Advanced level
Which statements about sodium nitroprusside, Na2[Fe(CN)5NO], and its reaction with sulphide are correct? (Treat NO as NO+.) One or more options may be correct. JEE Advanced level
Sodium carbonate extract is acidified with dilute HNO3, boiled, and treated with AgNO3. A pale yellow curdy precipitate P forms. P is only sparingly soluble in ... JEE Advanced level
Nitrite in a sample is first confirmed by the Griess test (a red azo dye forms). The nitrite is then removed by warming the acidified solution with urea: 2HNO2 ... JEE Advanced level
Which statements about Prussian blue, Fe4[Fe(CN)6]3, are correct? One or more options may be correct. JEE Advanced level
A sodium salt gives a fruity smell on warming with ethanol and concentrated H2SO4 and a deep red colour with neutral FeCl3. Assuming the acid is liberated by H2... JEE Advanced level
A white curdy precipitate with AgNO3 that readily dissolves in dilute aqueous ammonia indicates the presence of NEET level
A yellow precipitate formed with AgNO3 is insoluble even in concentrated ammonia. The anion present is NEET level
When NaCl, K2Cr2O7 and conc. H2SO4 are heated together, dark red vapours are formed. The vapour is NEET level
In the brown ring test the complex [Fe(H2O)5NO]^2+ is formulated with NO as NO+. The oxidation state of iron is JEE Main level
Before the brown ring test for nitrate, Br^- and I^- must be removed because JEE Main level
AgCl dissolves in ammonia: AgCl + 2NH3 <=> [Ag(NH3)2]+ + Cl-. Take K_sp(AgCl) = 1.8x10^-10 and K_f([Ag(NH3)2]+) = 1.6x10^7. The equilibrium [NH3] needed to just... JEE Main level
Assertion (A): Mercury(II) chloride does not give the chromyl chloride test. Reason (R): HgCl2 is largely covalent and furnishes very few free chloride ions in ... JEE Main level
Chromyl chloride vapour from the test is passed into aqueous NaOH to give a yellow solution via CrO2Cl2 + 4OH- -> CrO4^2- + 2Cl- + 2H2O. The oxidation states of... JEE Main level
Match the reaction in List I with the colour of the precipitate in List II. List I: (i) I- with Pb(NO3)2; (ii) S^2- with Pb(NO3)2; (iii) Br- with AgNO3; (iv) SO... JEE Main level
In a chromyl chloride test, 1.30 g of NaCl is heated with excess K2Cr2O7 and conc. H2SO4: K2Cr2O7 + 4NaCl + 6H2SO4 -> 2CrO2Cl2 + 2KHSO4 + 4NaHSO4 + 3H2O. All th... JEE Advanced level
In the brown ring complex [Fe(H2O)5NO]^2+, formulated as iron bound to NO+, the nitrogen of nitrate changes from +5 to +3 in NO+. Treating the weak-field aqua c... JEE Advanced level
A solution contains both NaNO2 and NaNO3. Which procedure correctly establishes the presence of nitrate? JEE Advanced level
A white salt X gives a lilac flame (violet through cobalt glass). It gives no gas with dilute H2SO4. With conc. H2SO4 and MnO2 it gives a yellow-green gas, and ... JEE Advanced level
Which of the following precipitates dissolve readily in cold dilute (about 2 M) aqueous ammonia? JEE Advanced level
Which statements about the chromyl chloride test are correct? JEE Advanced level
Select the correct statements about the oxidation state of iron (taking NO as NO+ where present). JEE Advanced level
Which of the following observations with lead nitrate solution are correct? JEE Advanced level