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प्रश्न
Write balanced chemical equations for the conversion of `CrO_4^(2-)` to `Cr_2O_7^(2-)` in acidic medium and `Cr_2O_7^(2-)` to `CrO_4^(2-)`
in basic medium.
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उत्तर
`K_2Cr_2O_7 + 2KOH -> 2K_2CrO_4 + H_2O`
`2K_2CrO_4 + 2HCl -> K_2Cr_2O_7 + 2KCl + H_2O`
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संबंधित प्रश्न
Account for the following:
Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows oxidation state of +4.
Account for the following:
Cr2+ is a strong reducing agent.
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.
How would you account for the following:
Of the d4 species, Cr2+ is strongly reducing while manganese (III) is strongly oxidising.
Calculate the number of unpaired electrons in the following gaseous ions:
Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in an aqueous solution?
Use Hund’s rule to derive the electronic configuration of Ce3+ ion and calculate its magnetic moment on the basis of ‘spin-only’ formula.
Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22, Cu = 29)
The paramagnetic character in the 3d-transition series elements increases up to Mn and then decreases.
Account for the following :
Ti4+ is colourless whereas V4+ is coloured in an aqueous solutions.
Which is the most stable oxidation state of iron?
Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d5. What is its atomic number?
The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of \[\ce{Cr^{3+}}\] ion is ______.
Although fluorine is more electronegative than oxygen, but the ability of oxygen to stabilise higher oxidation states exceeds that of fluorine. Why?
A solution of \[\ce{KMnO4}\] on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
The second and third rows of transition elements resemble each other much more than they resemble the first row. Explain why?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
While filling up of electrons in the atomic orbitals, the 4s orbital is filled before the 3d orbital but reverse happens during the ionisation of the atom. Explain why?
Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Because it has positive electrode potential.
Account for the following:
In case of transition elements, ions of the same charge in a given series show progressive decrease in radius with increasing atomic number.
It has been observed that first ionization energy of 5 d series of transition elements are higher than that of 3d and 4d series, explain why?
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, the change in ethalpy for combustion of C2H4 is equal to
Mercury is the only metal liquid at room temperature due to its:-
Consider the following standard electrode potentials (E° in volts) in aqueous solution:
| Element | M3+/M | M+/M |
| Al | - 1.66 | +0.55 |
| Tl | + 1.26 | -0.34 |
Based on these data, which of the following statements is correct?
Which of the following characteristics of transition metals is associated with their catalytic activity?
Account for the following:
Sc3+ is colourless whereas Ti3+ is coloured in an aqueous solution.
Account for the following:
Ce4+ is a strong oxidising agent.
Assertion (A): Transition metals have high enthalpy of atomisation.
Reason (R): Greater number of unpaired electrons in transition metals results in weak metallic bonding.
Explain the magnetic properties of d-block (or transition) elements.
Why are interstitial compounds well known for transition metals?
Match List-I with List-II.
| List-I | List-II |
| A. Haber process | I. Fe catalyst |
| B. Wacker oxidation | II. PdCl2 |
| C. Wilkinson catalyst | III. [(PPh3)3RhCl] |
| D. Ziegler catalyst | IV. TiCl4 with Al(CH3)3 |
Choose the correct answer from the options given below:
