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प्रश्न
Which of the following reactions are disproportionation reactions?
(a) \[\ce{Cu^{+} -> Cu^{2+} + Cu}\]
(b) \[\ce{3MnO^{-}4 + 4H^{+} -> 2MnO^{-}4 + MnO2 + 2H2O}\]
(c) \[\ce{2KMnO4 -> K2MnO4 + MnO2 + O2}\]
(d) \[\ce{2MnO^{-}4 + 3Mn^{2+} + 2H2O -> 5MnO2 + 4H^{+}}\]
विकल्प
a, b
a, b, c
b, c, d
a, d
उत्तर
a, b
Explanation:
(a) \[\ce{\overset{+1}{Cu+} -> \overset{+2}{Cu^{2+}} + \overset{0}{Cu}}\]
(b) \[\ce{\overset{+6}{3MnO^{-}4} + 4H^{+} -> \overset{+2}{2MnO^{-}4} + \overset{+4}{MnO2} + 2H2O}\]
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संबंधित प्रश्न
Complete the following equation:
\[\ce{2MnO4- + 6H+ + 5NO2- ->}\]
When chromite ore FeCr2O4 is fused with NaOH in presence of air, a yellow-coloured compound (A) is obtained, which on acidification with dilute sulphuric acid gives a compound (B). Compound (B) on reaction with KCl forms an orange coloured crystalline compound (C).
(i) Write the formulae of the compounds (A), (B) and C.
(ii) Write one use of compound (C).
Name a member of the lanthanoid series that is well-known to exhibit +2 oxidation state.
Answer the following question.
When MnO2 is fused with KOH in the presence of KNO3 as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in an acidic solution to give a purple compound (B). An alkaline solution of compound (B) oxidizes KI to compound (C) whereas an acidified solution of compound (B) oxidizes KI to (D). Identify (A), (B), (C), and (D).
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(iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.
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\[\ce{Cr2O^{2-}7 + 3H2S + 8H^+ ->}\]
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Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
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