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प्रश्न
Why does copper not replace hydrogen from acids?
उत्तर
The value of standard reduction potential of copper (E° = + 0.34 V) is positive. Therefore, copper does not liberate hydrogen from acids.
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संबंधित प्रश्न
What may be the stable oxidation state of the transition element with the following d electron configurations in the ground state of their atoms?
3d3, 3d5, 3d8 and 3d4
Explain why:
(i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state.
(At. no. of Mn = 25, Fe = 26)
(ii) Transition elements usually form coloured ions.
(iii) Zr and Hf exhibit similar properties.
(At. no. of Zr = 40, Hf = 72)
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: Cations of transition elements occur in various valence states.
Reason: Large number of oxides of transition elements are possible.
Metallic radii of some transition elements are given below. Which of these elements will have highest density?
| Element | \[\ce{Fe}\] | \[\ce{Co}\] | \[\ce{Ni}\] | \[\ce{Cu}\] |
| Metallic radii/pm | 126 | 125 | 125 | 128 |
Answer the following question:
Which element of the first transition series has highest second ionisation enthalpy?
Identify the metal and justify your answer.
\[\ce{MO3F}\]
The standard electrode potentials of four elements A, B, C and D are – 3.05, – 1.66, – 0.40 and + 0.80. The highest chemical reactivity will be exhibited by
Which of the following species has maximum magnetic momentum?
Among the following pairs of ions, the lower oxidation state in aqueous solution is more stable than the other in:-
Why is the `"E"_(("V"^(3+)//"V"^(2+)))^"o"` value for vanadium comparatively low?
