Colour and magnetic properties

55 questions on Colour and magnetic properties from the d- and f-Block Elements chapter: 11 NEET level, 22 JEE Main, 22 JEE Advanced. Each one opens with its answer and solution.

• Which of the following ions is colourless in aqueous solution? NEET level
• The spin-only magnetic moment of Cu^2+ (Z = 29) is, using mu = sqrtn(n+2) BM: NEET level
• The number of unpaired electrons in Mn^2+ (Z = 25) is: NEET level
• Which of the following ions is diamagnetic? NEET level
• The intense purple colour of aqueous KMnO4 is due to: NEET level
• Compounds of transition metals are generally coloured mainly because of: NEET level
• The colour of aqueous potassium chromate, K2CrO4, is: NEET level
• Paramagnetism of a substance is due to the presence of: NEET level
• Among the following ions, the highest spin-only magnetic moment is shown by: NEET level
• The colour of hexaaquacobalt(II) ion, [Co(H2O)6]^2+, in aqueous solution is: NEET level
• Hydrated copper(II) ion, [Cu(H2O)4]^2+, in aqueous solution is: NEET level
• The correct increasing order of spin-only magnetic moment for the ions Sc^3+, Ti^3+, V^3+, Cr^3+ is: JEE Main level
• Assertion (A): Aqueous solutions of zinc(II) salts are colourless. Reason (R): Zn^2+ has a completely filled 3d^10 configuration, so no d-d transition is possib... JEE Main level
• Assertion (A): Permanganate ion is intensely coloured although manganese in it has no d electron. Reason (R): The colour arises from ligand-to-metal charge tran... JEE Main level
• Match the aqueous ions in List I with the number of unpaired electrons in List II (high-spin configurations). List I: (P) Cu^2+, (Q) Ni^2+, (R) Co^2+, (S) Mn^2+... JEE Main level
• In aqueous solution, the colour of which of the following is due to d-d transitions and not charge transfer? JEE Main level
• The spin-only magnetic moment of the low-spin complex ion [Fe(CN)6]^3- is: JEE Main level
• When excess aqueous ammonia is added to pale blue aqueous Cu^2+, a deep blue solution of [Cu(NH3)4]^2+ forms. The absorption maximum shifts to a shorter wavelen... JEE Main level
• Which of the following nickel(II) or cobalt(II) complexes is diamagnetic? JEE Main level
• Among the following hydrated trivalent lanthanide ions, the one that is colourless is: JEE Main level
• The spin-only magnetic moment of Gd^3+ (Z=64, [Xe]4f^7) is: JEE Main level
• The very pale pink colour of [Mn(H2O)6]^2+ (high spin d^5) is explained by the fact that its d-d transitions: JEE Main level
• Which of the following pairs of high-spin aqueous ions have the same spin-only magnetic moment? JEE Main level
• Which of the following solids is white (colourless)? JEE Main level
• The spin-only magnetic moment of the weak-field complex ion [CoF6]^3- is: JEE Main level
• The green manganate ion MnO4^2- is: JEE Main level
• Match the hexaaqua ions in List I with their colours in List II. List I: (P) [Cu(H2O)6]^2+, (Q) [Ni(H2O)6]^2+, (R) [Co(H2O)6]^2+, (S) [Cr(H2O)6]^3+. List II: (1... JEE Main level
• Assertion (A): Aqueous Fe^2+ is paramagnetic with a spin-only magnetic moment of 4.90 BM. Reason (R): In [Fe(H2O)6]^2+, the 3d^6 electrons are all paired becaus... JEE Main level
• The tetrahedral complex [CoCl4]^2- is high spin and has three unpaired electrons. Taking mu=sqrtn(n+2) BM, calculate its spin-only magnetic moment in BM, to two... JEE Main level
• Which of the following aqueous high-spin ions are paramagnetic? JEE Main level
• The colour of which of the following species in aqueous solution arises from d-d transitions? JEE Main level
• Which of the following high-spin ions have a spin-only magnetic moment of 4.90 BM? JEE Main level
• Which of the following statements about trivalent lanthanide ions are correct? JEE Main level
• Green aqueous K2MnO4 is acidified and disproportionates: 3MnO4^2- + 4H^+ -> 2MnO4^- + MnO2 + 2H2O. The purple product in the solution is best described as: JEE Advanced level
• Aqueous Fe^2+ reacts with [Fe(CN)6]^3- to give the dark blue pigment Turnbull's blue, which is the same as Prussian blue, KFe[Fe(CN)6]. In this solid the carbon... JEE Advanced level
• Aqueous sodium hydroxide is added to orange Na2Cr2O7 solution to give a yellow solution of X: Cr2O7^2- + 2OH^- -> 2CrO4^2- + H2O. X is then reduced by a stoichi... JEE Advanced level
• Consider the aqueous high-spin M^2+ ions of the 3d series from Ti^2+ to Zn^2+ (nine ions). The number of these ions whose spin-only magnetic moment exceeds 4 BM... JEE Advanced level
• The ratio of the spin-only magnetic moment of [Fe(H2O)6]^3+ to that of [Fe(CN)6]^3- is closest to: JEE Advanced level
• Pink aqueous [Co(H2O)6]^2+ turns deep blue on adding concentrated HCl: [Co(H2O)6]^2+ + 4Cl^- -> [CoCl4]^2- + 6H2O. The blue species is: JEE Advanced level
• In K3[Mn(CN)6], cyanide is a strong-field ligand giving a low-spin octahedral complex. The oxidation state of Mn and the spin-only magnetic moment of the comple... JEE Advanced level
• Cuprous oxide dissolves in dilute sulfuric acid: Cu2O + 2H^+ -> Cu^2+ + Cu + H2O. The colour of the resulting solution and the spin-only magnetic moment of the ... JEE Advanced level
• Match the complexes in List I with the number of unpaired electrons in List II. List I: (P) [Fe(CN)6]^4-, (Q) [Fe(H2O)6]^2+, (R) [FeF6]^3-, (S) [Fe(CN)6]^3-. Li... JEE Advanced level
• Assertion (A): Replacing water by ethane-1,2-diamine turns the green [Ni(H2O)6]^2+ into violet [Ni(en)3]^2+, and both complexes have two unpaired electrons. Rea... JEE Advanced level
• It is observed empirically that Ln^3+ ions with 4f^n and 4f^(14-n) configurations have similar colours. Which pair of ions is expected to have similar colours? JEE Advanced level
• Aqueous copper(II) sulfate is treated with excess KI: 2Cu^2+ + 4I^- -> 2CuI + I2. The precipitate and the magnetic nature of copper in it are: JEE Advanced level
• Acidified KMnO4 reacts with just enough aqueous FeSO4: MnO4^- + 5Fe^2+ + 8H^+ -> Mn^2+ + 5Fe^3+ + 4H2O. Assuming high-spin aqua ions, the total number of unpair... JEE Advanced level
• A 3d metal M forms an aqueous M^3+ ion with spin-only magnetic moment 5.92 BM. The atomic number of M and the spin-only magnetic moment of the high-spin aqua M^... JEE Advanced level
• Using mu=sqrtn(n+2) BM, calculate the sum of the spin-only magnetic moments of one mole each of [Mn(H2O)6]^2+, [Fe(H2O)6]^3+ and [Ni(H2O)6]^2+ (all high spin), ... JEE Advanced level
• Which of the following complex ions have a spin-only magnetic moment of zero? JEE Advanced level
• Which of the following species in aqueous solution are both diamagnetic and coloured due to charge transfer? JEE Advanced level
• Mn(III) in water disproportionates: 2Mn^3+ + 2H2O -> Mn^2+ + MnO2 + 4H^+. Which statements are correct? JEE Advanced level
• Which of the following ions have a spin-only magnetic moment between 2.5 BM and 4.0 BM (high spin where applicable, aqueous)? JEE Advanced level
• Which of the following statements about the aqueous chromate-dichromate system are correct? JEE Advanced level
• Which of the following statements about the spectra and magnetism of trivalent lanthanide ions are correct? JEE Advanced level
• Which of the following complex ions have exactly two unpaired electrons? JEE Advanced level