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प्रश्न
In the form of dichromate, \[\ce{Cr (VI)}\] is a strong oxidising agent in acidic medium but \[\ce{Mo (VI)}\] in \[\ce{MoO3}\] \[\ce{and W (VI)}\] in \[\ce{WO3}\] are not because:
(i) \[\ce{Cr(VI)}\] is more stable than \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\].
(ii) \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\] are more stable than \[\ce{Cr(VI)}\].
(iii) Higher oxidation states of heavier members of group-6 of transition series are more stable.
(iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.
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उत्तर
(ii) \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\] are more stable than \[\ce{Cr(VI)}\].
(iii) Higher oxidation states of heavier members of group-6 of transition series are more stable.
Explanation:
In d-block elements, for heavier elements, the higher oxidation states are more stable. Hence, \[\ce{Mo(VI)}\] and \[\ce{W(VI)}\] are more stable than \[\ce{Cr(VI)}\]. That’s why, \[\ce{Cr(VI)}\] in the form of dichromate is a stronger oxidizing agent in acidic medium whereas \[\ce{MoO3}\] and \[\ce{WO3}\] are not.
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संबंधित प्रश्न
Complete the following equation:
\[\ce{2MnO4- + 6H+ + 5NO2- ->}\]
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Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?
Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with iron (II) ions? Write the ionic equation for the reaction.
Give an example and suggest a reason for the following feature of the transition metal chemistry:
The highest oxidation state is exhibited in oxoanions of a metal.
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(a) \[\ce{Cu^{+} -> Cu^{2+} + Cu}\]
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(c) \[\ce{2KMnO4 -> K2MnO4 + MnO2 + O2}\]
(d) \[\ce{2MnO^{-}4 + 3Mn^{2+} + 2H2O -> 5MnO2 + 4H^{+}}\]
\[\ce{KMnO4}\] acts as an oxidising agent in alkaline medium. When alkaline \[\ce{KMnO4}\] is treated with \[\ce{KI}\], iodide ion is oxidised to ______.
Potassium permanganate acts as an oxidant in neutral, alkaline as well as acidic media. The final products obtained from it in the three conditions are, respectively.
Why \[\ce{HCl}\] should not be used for potassium permanganate titrations?
Potassium permanganate on heating at 513 K gives a product which is ______.
Complete the following ionic equation:
\[\ce{Cr2O^{2-}7 + 2OH^- ->}\]
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Complete the reaction mentioning all the products formed:
\[\ce{2KMnO4 ->[\Delta]}\]
Complete the reaction mentioning all the products formed:
\[\ce{Cr2O^{2-}7 + 3H2S + 8H^+ ->}\]
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
