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10 months agoContributor-Level 10
18. Ce, Pr and Nd belong to the lanthanide series whereas Th, Pa and U belong to the actinides family.
When electrons start accommodating the 4f and 5f orbitals, the 5f electrons penetrate less into the inner core. They are more effectively shielded nuclei in comparison to 4f-electrons in lanthanides. This leads to the fact that 5f-electrons experience reduced nuclear force of attraction and hence they have Lower ionisation enthalpies than lanthanoids.
New answer posted
10 months agoContributor-Level 10
39. Option (ii) and (iii)
The froth floatation method is most commonly used for sulfide ore. Sulfide ores galena (PbS) and copper pyrites (CuFeS2) are found here.
New answer posted
10 months agoContributor-Level 10
38. Option (iii) and (iv)
Bauxite consists of many impurities like hematite, goethite, Fe2O3, the sand SiO2, etc.'
New answer posted
10 months agoContributor-Level 10
17. Magnetic moment of an electron/dipole moment is caused by its intrinsic properties of spin and electric charge. It depends upon the number of unpaired electrons in its valence shell. The more the number of unpaired electrons, the greater will be the value of magnetic moment.
Cr3+ = [Ar] 3d3 = 3 unpaired electrons
Co2+ = [Ar] 3d7 = 3 unpaired electrons
But as both the ions have the same no. of unpaired electrons, there's one other factor called orbital contribution which also influences the magnetic moment. As, the three unpaired electronic configuration is sy
New answer posted
10 months agoContributor-Level 10
37. Option (ii) and (iii)
It is possible to separate two sulfide ores using the froth floatation process by adjusting the proportion of oil to water or by using 'depressants.' In the case of an ore containing ZnS and PbS, for example, the depressant used is NaCN.
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10 months agoContributor-Level 10
16. Fluorine - 1s22s22p5
Oxygen - 1s2 2s2 2p6 3s2 3p6
As we can infer from the electronic configuration, fluorine only has one unpaired electron in its 2p-orbital which can be involved in formation of only one bond and fluorine lacks d-orbital.
While oxygen has d-orbitals in its configuration which allow the oxygen to form multiple bonds. Therefore, oxygen has greater stability to stabilise its oxidation states than fluorine.
New answer posted
10 months agoContributor-Level 10
36. Option (i) and (iii)
A suspension of powdered ore is made with water during the froth floatation process. Collectors and froth stabilizers are added to it. Collectors (e.g., pine oils, fatty acids, xanthates, etc.) improve the non wettability of the mineral particles, while froth stabilizers (e.g., cresols, aniline) keep the froth stable
New answer posted
10 months agoContributor-Level 10
15. The reactions are explained as:
MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O
(A) (B)
3Cl2 + 2NH3 → NCl3 + 3HCl
(excess) (C)
New answer posted
10 months agoContributor-Level 10
35. Option (i) and (ii)
In the extraction of alumina by Hall-Heroult's process, alumina is mixed with cryolite with the mixture of fluorspar \& fluoride that increases the conductivity of electrical and lowers the melting point of Al2O3 .
New answer posted
10 months agoContributor-Level 10
14. Higher enthalpy of hydration provides extra stability to Cu2+ oxidation state than +1 oxidation state.
Enthalpy of hydration is described as the amount of energy released on dilution of one mole of gaseous ions.
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