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प्रश्न
Explain, why lanthanum (Z = 57) forms La3+ ion, while cerium (Z = 58) forms Ce4+ ion?
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उत्तर
57La -Electronic configuration is [Xe]4f0 5d1 6s2
After losing 3 electrons La forms La3+ ion which is stable due to empty 4f-orbitals.
58Ce - Electronic configuration is [Xe]4f2 5d0 6s2
After losing 4 electrons Ce forms Ce4+ ion which is stable due to empty 4f-orbitals.
Thus, lanthanum (Z = 57) forms La3+ ion, while cerium (Z = 58) forms Ce4+ ion.
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संबंधित प्रश्न
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| Column I (Compound/element) | Column II (Use) | |
| (i) | Lanthanoid oxide | (a) Production of iron alloy |
| (ii) | Lanthanoid | (b) Television screen |
| (iii) | Misch metal | (c) Petroleum cracking |
| (iv) | Magnesium based alloy is constituent of | (d) Lanthanoid metal + iron |
| (v) | Mixed oxides of lanthanoids are employed | (e) Bullets |
| (f) In X-ray screen |
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| Column I | Column II | |
| (i) | Oxidation state of Mn in MnO2 is | (a) + 2 |
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| (iii) | Most stable oxidation state of | (c) + 4 |
| Mn in oxides is | (d) + 5 | |
| (iv) | Characteristic oxidation state of lanthanoids is | (e) + 7 |
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Radii of 4d and 5d block elements.
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