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प्रश्न
Although +3 is the characteristic oxidation state for lanthanoids but cerium also shows +4 oxidation state because:
(i) it has variable ionisation enthalpy
(ii) it has a tendency to attain noble gas configuration
(iii) it has a tendency to attain f 0 configuration
(iv) it resembles Pb4+
उत्तर
(ii) it has a tendency to attain noble gas configuration
(iii) it has a tendency to attain f 0 configuration
Explanation:
Electronic configuration of cerium:
\[\ce{Ce - 4f^1 5d^1 6s^2}\]
\[\ce{Ce^4+ − 4f^0 5d^0 6s^0}\]
Lead has the tendency to lose its four outer electrons to attain Noble gas configuration and this removal of electrons corresponds to the f∘ configuration and cause it to be stable in +4 oxidation state.
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संबंधित प्रश्न
Define lanthanoid contraction.
Account for the following :
Zr and Hf have almost similar atomic radii.
Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.
Explain the cause of lanthanoid contraction?
Account for the following:
Zn, Cd and Hg are soft metals.
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?
Match the statements given in Column I with the oxidation states given in Column II.
| Column I | Column II | |
| (i) | Oxidation state of Mn in MnO2 is | (a) + 2 |
| (ii) | Most stable oxidation state of Mn is | (b) + 3 |
| (iii) | Most stable oxidation state of | (c) + 4 |
| Mn in oxides is | (d) + 5 | |
| (iv) | Characteristic oxidation state of lanthanoids is | (e) + 7 |
Match the property given in Column I with the element given in Column II.
| Column I (Property) | Column II (Element) | |
| (i) | Lanthanoid which shows +4 oxidation state |
(a) Pm |
| (ii) | Lanthanoid which can show +2 oxidation state |
(b) Ce |
| (iii) | Radioactive lanthanoid | (c) Lu |
| (iv) | Lanthanoid which has 4f7 electronic configuration in +3 oxidation state |
(d) Eu |
| (v) | Lanthanoid which has 4f14 electronic configuration in +3 oxidation state |
(e) Gd |
| (f) Dy |
On the basis of Lanthanoid contraction, explain the following:
Nature of bonding in \[\ce{La2O3}\] and \[\ce{Lu2O3}\] .
Assertion: There is a continuous increase in size among Lanthanoids with an increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction.
