Dilute acid group anions: carbonate, sulphite, sulphide, nitrite

37 questions on Dilute acid group anions: carbonate, sulphite, sulphide, nitrite from the Qualitative Analysis: Anions chapter: 8 NEET level, 16 JEE Main, 13 JEE Advanced. Each one opens with its answer and solution.

• A salt on treatment with dilute H2SO4 evolves a colourless, odourless gas that turns lime water milky. The anion is NEET level
• A gas evolved on adding dilute H2SO4 to a salt has a rotten-egg smell and turns filter paper moistened with lead acetate black. The anion present is NEET level
• On adding dilute H2SO4 to a salt, a pale brown vapour appears at the mouth of the tube. The anion is most likely NEET level
• A salt gives a vinegar-like smell on warming with dilute H2SO4 and a deep red colour with neutral FeCl3 solution. The anion is NEET level
• Acidified potassium dichromate solution (orange) turns green when SO2 is passed through it: Cr2O7^2- + 3SO2 + 2H+ -> 2Cr^3+ + 3SO4^2- + H2O. How many moles of S... JEE Main level
• A mixture of 4.20 g of NaHCO3 and 2.65 g of Na2CO3 is treated with excess dilute H2SO4 and all the CO2 evolved is passed into excess lime water. Atomic masses: ... JEE Main level
• Sodium nitroprusside solution gives a purple colour in alkaline medium with the sulphide ion. Which anion gives this purple colour with this reagent without any... JEE Main level
• A colourless gas evolved on warming a sodium salt with dilute H2SO4 turns acidified dichromate paper green, and a pale yellow turbidity also develops in the sol... JEE Main level
• In the reaction 2NO2^- + 2I^- + 4H+ -> 2NO + I2 + 2H2O used in the starch-iodide test for nitrite, the oxidising agent and the change in oxidation state of nitr... JEE Main level
• Assertion: Dilute H2SO4 liberates CO2 from the cold solid of both a carbonate and a hydrogencarbonate. Reason: A cold solution of MgSO4 gives an immediate white... JEE Main level
• The gas formed from sodium sulphite and dilute H2SO4 turns lime water milky and decolourises acidified KMnO4: 2MnO4^- + 5SO2 + 2H2O -> 2Mn^2+ + 5SO4^2- + 4H+. T... JEE Main level
• Which of the following statements are correct for tests with dilute H2SO4 (warm if necessary)? JEE Advanced level
• After a salt is treated with dilute H2SO4, a colourless gas is collected. Which of the following tests distinguish SO2 (from a sulphite) from CO2 (from a carbon... JEE Advanced level
• The sodium salt X with warm dilute H2SO4 gives a pungent colourless gas that turns acidified dichromate paper green and a pale yellow turbidity. With excess AgN... JEE Advanced level
• In sodium nitroprusside Na2[Fe(CN)5NO], treat NO as the nitrosonium ligand NO+. With sulphide ions in alkaline solution, a purple complex Na4[Fe(CN)5NOS] forms.... JEE Advanced level
• A sodium salt X with dilute H2SO4 evolves a gas that blackens lead acetate paper. The gas, passed into aqueous SO2, gives a yellow precipitate: 2H2S + SO2 -> 3S... JEE Advanced level
• A sodium salt X decolourises acidified KMnO4, gives a brown vapour at the mouth of the tube with dilute H2SO4 and turns starch-iodide paper blue after acidifica... JEE Advanced level
• Which of the following statements about the thiosulphate ion are correct? JEE Advanced level
• A colourless, odourless gas is evolved when a salt is treated with dilute H2SO4 and it turns lime water milky. The gas is NEET level
• A salt on warming with dilute H2SO4 evolves a gas that turns a filter paper moistened with lead acetate black. The anion present is NEET level
• A few drops of freshly prepared sodium nitroprusside solution are added to an alkaline solution of sodium sulphide. The colour developed is NEET level
• Sodium nitrite is warmed with dilute H2SO4. A colourless gas is evolved that turns reddish brown on coming in contact with air. The colourless gas is NEET level
• A paper moistened with acidified potassium dichromate turns green when exposed to SO2 evolved from sodium sulphite and dilute H2SO4. The balanced change is Cr2O... JEE Main level
• Both sodium carbonate and sodium sulphite give a gas that turns lime water milky when treated with dilute H2SO4. Which observation with the evolved gas distingu... JEE Main level
• Which test mixture gives a brown colouration at room temperature with sodium nitrite solution but no brown colouration or ring with sodium nitrate solution? JEE Main level
• A sodium salt on treatment with dilute HCl gives a pale yellow turbidity and a gas with a pungent smell of burning sulphur on warming. The anion is JEE Main level
• Assertion (A): A paper moistened with acidified potassium dichromate turns green in both SO2 and H2S. Reason (R): Both gases are reducing agents that reduce Cr(... JEE Main level
• Match the gases in List I with the observation in List II. List I: (i) CO2; (ii) SO2; (iii) H2S; (iv) NO2. List II: (p) rotten-egg odour, blackens lead acetate ... JEE Main level
• In the Griess-type test for nitrite, sulphanilic acid is treated with the test solution in acetic acid and then 1-naphthylamine is added to give a red dye. The ... JEE Main level
• A colourless solution Y effervesces with dilute acid. With cold MgSO4 solution Y gives no precipitate, but on boiling a white precipitate forms and gas is evolv... JEE Main level
• Sodium nitrite (NaNO2) of mass 4.14 g is treated with excess potassium iodide in acetic acid, 2NO2^- + 2I^- + 4H+ -> 2NO + I2 + 2H2O. Calculate the mass of iodi... JEE Main level
• Sodium nitroprusside, Na2[Fe(CN)5NO], is used in the test for sulphide. Taking NO as NO+, which statements are correct? JEE Advanced level
• A white sodium salt X, when warmed with dilute H2SO4, gives a pungent gas that turns acidified dichromate paper green and a pale yellow turbidity, and no gas bl... JEE Advanced level
• A sodium salt X gives a colourless pungent gas with dilute H2SO4. The gas turns lime water milky, the milkiness disappears on passing excess gas, and the gas de... JEE Advanced level
• Which statements about nitrite are correct? JEE Advanced level
• A solid is a mixture of Na2CO3 and Na2SO3. It is warmed with dilute H2SO4 and the evolved gas mixture is to be tested for CO2 in the presence of SO2. Which proc... JEE Advanced level
• Which of the following correctly describe the behaviour of H2S gas liberated from sulphide with dilute acid? JEE Advanced level