Important compounds: KMnO4 and K2Cr2O7

28 questions on Important compounds: KMnO4 and K2Cr2O7 from the d- and f-Block Elements chapter: 6 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• The green colour of potassium manganate is due to the presence of the ion NEET level
• In acidic medium, MnO4^- is finally reduced to NEET level
• On adding aqueous sodium hydroxide to orange potassium dichromate solution, the solution turns NEET level
• The principal ore from which potassium permanganate is manufactured is NEET level
• The ore used for the commercial preparation of potassium dichromate is NEET level
• For titrating Fe^2+ against KMnO4, the medium used is acidified with NEET level
• When KMnO4 oxidises potassium iodide in a neutral or weakly alkaline medium, the iodine-containing product is JEE Main level
• How many moles of Fe^2+ are oxidised to Fe^3+ by one mole of Cr2O7^2- in acidic solution? JEE Main level
• Assertion (A): In the titration of Fe^2+ with KMnO4, dilute nitric acid is not used to acidify the solution. Reason (R): Nitric acid is a reducing agent and wou... JEE Main level
• Solid NaCl is heated with K2Cr2O7 and concentrated H2SO4. The orange-red vapours evolved are of JEE Main level
• Match the condition for KMnO4 in Column I with the species formed or evolved in Column II. Column I: (P) acidic medium (Q) neutral medium (R) strongly alkaline ... JEE Main level
• Which statement correctly describes what happens when alkali is added to an orange acidified solution of K2Cr2O7? JEE Main level
• The colour of the permanganate ion, in which manganese has the 3d^0 configuration, arises from JEE Main level
• In the titration of oxalic acid with acidified KMnO4 at about 60 degC, the first few drops decolourise slowly but later drops decolourise rapidly. This is becau... JEE Main level
• In acidic medium, KMnO4 reacts with H2O2 as 2MnO4^- + 5H2O2 + 6H^+ -> 2Mn^2+ + 5O2 + 8H2O. The number of moles of O2 released per mole of KMnO4 is JEE Main level
• In the roasting of chromite, 4FeCr2O4 + 8Na2CO3 + 7O2 -> 8Na2CrO4 + 2Fe2O3 + 8CO2. The number of moles of O2 consumed per mole of chromite is JEE Main level
• When SO2 is passed through an acidified solution of potassium dichromate, the observed colour change is JEE Main level
• Using atomic masses Fe = 56 and O = 16, 23.2 g of Fe3O4 is dissolved in dilute H2SO4 (no oxidation takes place during dissolution). The volume of 0.100 M KMnO4 ... JEE Advanced level
• Pyrolusite is fused with KOH and KNO3 to give a green compound X. X on acidification (or by passing CO2) gives a purple compound Y and a brown precipitate Z. Us... JEE Advanced level
• Orange solution A turns yellow (B) with NaOH. B gives a yellow precipitate C with Pb(NO3)2. Acidified A with H2O2 and ether gives a blue ether-soluble compound ... JEE Advanced level
• 0.490 g of K2Cr2O7 (molar mass 294 g mol^-1) is treated with excess KI in dilute H2SO4 and the liberated iodine is titrated with 0.100 M Na2S2O3 (I2 + 2S2O3^2- ... JEE Advanced level
• 0.800 g of pure ferrous oxalate, FeC2O4 (Fe = 56, C = 12, O = 16), is dissolved in dilute H2SO4. Both Fe^2+ and the oxalate are oxidised by 0.0200 M KMnO4 in ac... JEE Advanced level
• Select the correct statements about permanganate and manganate. JEE Advanced level
• Select the correct statements about potassium dichromate and the dichromate ion. JEE Advanced level
• Acidified K2Cr2O7 (dilute H2SO4) is used in the following conversions. Which of them are correct? JEE Advanced level
• Select the correct reactions of acidified KMnO4 (dilute H2SO4 medium). JEE Advanced level
• Select the correct statements regarding the preparation of potassium permanganate. JEE Advanced level
• Using K = 39, Mn = 55, Cr = 52 and O = 16, select the correct equivalent masses. JEE Advanced level