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The d & f Block Elements — Chemistry STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements5 Marks
Question
  1. Account for the following:
  1. Mn2O7 is acidic whereas MnO is basic.
  2. Though copper has completely filled d-orbital (d10) yet it is considered as a transition metal.
  3. Actinoids show wide range of oxidation states.
  1. Write the preparation of potassium permanganate from pyrolusite ore (MnO2).
✓

Answer

  1.  
  1. Because of higher oxidation state (+7) of Mn.
  2. Because it has one unpaired electron in 3d orbital in its +2 oxidation state / or it has incompletely filled d-orbital in +2 oxidation state.
  3. Because of comparable energies of 5f, 6d and 7s orbitals.
  1. $2\text{MnO}_2\text{ }+\text{ }4\text{KOH}\text{ }+\text{ }\text{O}_2\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }}2\text{K}_2\text{MnO}_4\text{ }+\text{ }2\text{H}_2\text{O}$

$3\text{MnO}_4\text{ }^{2-}+\text{ }4\text{H}^+\text{ }\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }}2\text{MnO}_4\text{ }^-+\text{MnO}_2+\text{ }2\text{H}_2\text{O}$

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