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प्रश्न
Complete the following chemical equations:
`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`
`(ii) 2CrO_4^(2-)+2H^+ ->`
`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`
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उत्तर
` (i)6Fe^(2+)+Cr_2O_7^(2-)+14H^+ -> 2Cr^(3+)+6Fe^(3+)+7H_2O`
(ii) 2CrO42- + 2H+ → Cr2O72- + H2O
(iii) 2MnO4- + 5C2O42- + 16H+ → 2Mn2+ + 10CO2 + 8H2O
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संबंधित प्रश्न
To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.
What may be the stable oxidation state of the transition element with the following d electron configuration in the ground state of its atom?
3d3
Which of the d-block elements may not be regarded as the transition elements?
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Crystal structure of oxides of transition metals often show defects.
Reason: Ligand field effect cause distortions in crystal structures.
Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d5. What is its atomic number?
On adding NaOH, solution to the aqueous solution of K2CrO7 the colour of the solution changes from
Account for the following:
Transition metals form alloys.
Assertion (A): Transition metals have high enthalpy of atomisation.
Reason (R): Greater number of unpaired electrons in transition metals results in weak metallic bonding.
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
