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Group V and VI cations (Ba, Sr, Ca, Mg) and NH4+

47 questions on Group V and VI cations (Ba, Sr, Ca, Mg) and NH4+ from the Qualitative Analysis: Cations chapter: 9 NEET level, 19 JEE Main, 19 JEE Advanced. Each one opens with its answer and solution.

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Which reagent is used as the group reagent for Group V cations (Ba^2+, Sr^2+, Ca^2+)? NEET level
A salt imparts an apple-green colour to a non-luminous Bunsen flame. The cation present is NEET level
On adding Nessler's reagent to a solution containing NH4+ ions, the observation is a NEET level
Which compound is formed as a white crystalline precipitate when Na2HPO4 is added to a solution of Mg^2+ containing NH4Cl and NH4OH? NEET level
NH4Cl is added before (NH4)2CO3 in the group V separation mainly to NEET level
Among the following cations, the one that gives a crimson-red flame is NEET level
The test for NH4+ is always performed on a portion of the original solution (with NaOH or Nessler's reagent), and not on the filtrate from later groups, because JEE Main level
A solution of the group V carbonates in hot dilute acetic acid is treated with K2CrO4 solution. A yellow precipitate forms. The precipitate and the cation it co... JEE Main level
Which single reagent distinguishes Sr^2+ from Ca^2+ by giving a white precipitate (slowly, on standing) with Sr^2+ only, when added to a clear, acid-free aqueou... JEE Main level
A white precipitate obtained on adding NaOH to a Mg^2+ solution is adsorbed with the dye magneson I (p-nitrobenzene-azo-resorcinol). The observation is JEE Main level
Nessler's reagent is correctly described as JEE Main level
Assertion (A): The test for NH4+ must be carried out with a portion of the original solution. Reason (R): Ammonium salts are added as reagents in the group III ... JEE Main level
Match the tests in Column I with the observations in Column II. Column I: (P) NH4+ with Nessler's reagent; (Q) Mg^2+ with Na2HPO4 in NH4Cl/NH4OH; (R) Ca^2+ with... JEE Main level
Which of the following white precipitates dissolve in dilute acetic acid? (Select all that apply.) JEE Main level
A solution contains Mg^2+ in the presence of a high concentration of NH4Cl. On adding excess aqueous ammonia, no precipitate of Mg(OH)2 appears. The best explan... JEE Main level
50.0 mL of a solution that is 0.0800 M in Ba^2+ and 0.0600 M in Sr^2+ is treated with excess (NH4)2CO3 in the presence of NH4Cl and NH4OH. Assuming complete pre... JEE Main level
A solution is 0.020 M in each of Ba^2+ and Sr^2+. Solid Na2SO4 is added gradually with no change in volume. Take K_sp(BaSO4) = 1.0x10^-10 and K_sp(SrSO4) = 3.0x... JEE Main level
A white water-soluble salt A gives an apple-green flame. Its solution gives (i) a white precipitate with dilute H2SO4 insoluble in dilute HNO3, (ii) a yellow pr... JEE Advanced level
A solution is 0.10 M in each of Ca^2+ and Mg^2+. The carbonate ion concentration is raised slowly (no volume change). Take K_sp(CaCO3) = 3.0x10^-9 and K_sp(MgCO... JEE Advanced level
Assertion (A): Group V carbonates are dissolved in acetic acid, and not in dilute H2SO4, before the chromate test for Ba^2+. Reason (R): Dilute H2SO4 would conv... JEE Advanced level
Excess alkaline K2HgI4 reacts with 10.2 mg of NH3 according to 2K2HgI4 + NH3 + 3KOH -> HgO.Hg(NH2)I + 7KI + 2H2O. Atomic masses: Hg 200, I 127, N 14, O 16, H 1.... JEE Advanced level
A solution of a mixture is made alkaline with NH4OH in the presence of NH4Cl and treated with (NH4)2CO3 (commercial ammonium carbonate contains bicarbonate/carb... JEE Advanced level
A solution is 0.010 M in each of Ba^2+, Sr^2+ and Ca^2+. Solid Na2SO4 is added gradually (no volume change). Take K_sp: BaSO4 = 1.1x10^-10, SrSO4 = 3.2x10^-7, C... JEE Advanced level
A sample containing 0.150 g of magnesium (as Mg^2+) is precipitated as Mg(NH4)PO4.6H2O and ignited strongly: 2Mg(NH4)PO4 -> Mg2P2O7 + 2NH3 + H2O. Atomic masses:... JEE Advanced level
A colourless solution is tested. (i) Warming the original solution with NaOH gives a gas that turns Nessler's reagent brown. (ii) After the usual earlier groups... JEE Advanced level
Which statements about magnesium ammonium phosphate, formed in the group VI test, are correct? JEE Advanced level
In the bismuthate test, 0.020 mol of Mn^2+ is completely oxidised to MnO4- in nitric acid by solid NaBiO3 (Bi goes from +5 to +3). The minimum mass of NaBiO3 re... JEE Advanced level
Zinc(II) and manganese(II) are not precipitated by H2S in group II (in 0.3 M HCl) but appear in group IV. Which statements are correct? JEE Advanced level
The group reagent used to precipitate group V cations (Ba^2+, Sr^2+, Ca^2+) as carbonates is NEET level
The flame colour imparted by barium salts is NEET level
Nessler's reagent is NEET level
Among Ba^2+, Sr^2+ and Ca^2+ (as separate dilute solutions), the one that gives no precipitate with freshly prepared saturated CaSO4 solution is JEE Main level
Barium is separated from strontium and calcium by adding K2CrO4 to a solution buffered with CH3COOH/CH3COONa. The buffer is used because JEE Main level
In the group VI test, Mg^2+ with Na2HPO4 in presence of NH4Cl and excess NH3 gives a white crystalline precipitate of JEE Main level
Assertion (A): Mg^2+ is not precipitated by (NH4)2CO3 in presence of NH4Cl in group V. Reason (R): NH4+ lowers [CO3^2-] through NH4+ + CO3^2- <=> NH3 + HCO3-, a... JEE Main level
The brown precipitate in the Nessler test is formed by NH4+ + 2[HgI4]^2- + 4OH- -> HgO.Hg(NH2)I + 7I- + 3H2O. The number of moles of iodide ions liberated per m... JEE Main level
A 5.00 g sample containing only (NH4)2SO4 and Na2SO4 is heated with excess NaOH ((NH4)2SO4 + 2NaOH -> Na2SO4 + 2NH3 + 2H2O). It releases 0.616 L of NH3 at STP (... JEE Main level
Match the reagent-cation test in Column I with the observation in Column II. Column I: (P) Ba^2+ + K2CrO4 (acetic acid); (Q) Ca^2+ + (NH4)2C2O4; (R) Mg^2+ + mag... JEE Main level
Which cations are precipitated as carbonates by (NH4)2CO3 in presence of NH4Cl and NH4OH? JEE Main level
A solution contains 0.010 M each of Ba^2+ and Sr^2+. Solid K2CrO4 is added slowly (no volume change). Take K_sp: BaCrO4 1.2x10^-10, SrCrO4 2.2x10^-5. The [Ba^2+... JEE Advanced level
A white anhydrous salt Y gives an apple-green flame, a white precipitate with dilute H2SO4 insoluble in HCl, and a yellow precipitate with K2CrO4 in acetic acid... JEE Advanced level
Which statements about the sulphates and carbonates of group V and VI metals are correct? JEE Advanced level
The Mg2+ test with magneson is carried out in alkaline solution. For 0.010 M Mg^2+ (K_sp of Mg(OH)2 = 5.6x10^-12), Mg(OH)2 just starts to form at a pH of about,... JEE Advanced level
A solution containing 0.535 g of NH4Cl is boiled with excess NaOH, and the ammonia evolved is absorbed completely in excess Nessler's reagent. The brown product... JEE Advanced level
For the group V precipitation by (NH4)2CO3, which conditions are correct? JEE Advanced level
Which statements about the Nessler's test for NH4+ are correct? JEE Advanced level
A solution contains 0.0100 mol each of Ba^2+, Sr^2+ and Ca^2+. It is treated successively with (1) K2CrO4 in acetic acid buffer, giving BaCrO4; (2) (NH4)2SO4 on... JEE Advanced level