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प्रश्न
What are chemical twins? Write ‘two’ examples.
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उत्तर
Chemical twins are those in which the properties of some elements are same. Atomic size of Zr and Hf , Nb and Ta are similar. This is due to Lanthanide contraction.
Example - Zr and Hf ; Nb and Ta
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संबंधित प्रश्न
Define lanthanoid contraction.
What are lanthanoids?
Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.
What are the different oxidation states exhibited by the lanthanoids?
Compare the chemistry of actinoids with that of lanthanoids with special reference to electronic configuration.
Compare the chemistry of actinoids with that of the lanthanoids with special reference to oxidation state.
Compare the chemistry of actinoids with that of the lanthanoids with special reference to chemical reactivity.
Write the electronic configuration of the element with the atomic number 61.
Explain, why lanthanum (Z = 57) forms La3+ ion, while cerium (Z = 58) forms Ce4+ ion?
Explain effects of lanthanoid contraction.
What is lanthanoid contraction? Write the.............
The f-block elements are known as ____________.
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?
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 \[\ce{Lu2O3}\] .
How would you account for the following:
There is a greater range of oxidation states among the actinoids than among the lanthanides.
In lanthanoid the last electron enters (n - 2)f subshell where n is equal to ______.
The lathanide ion that would show colour is ______.
Mischmetal is an alloy consisting mainly of ______.
Cerium (Z = S8) is an important member of lanthanoids. Which of the following statements about cerium is incorrect?
State a reason for the following:
La(OH)3 is more basic than Lu(OH)3.
Why is Mn2+ ion more stable than Fe2+ ion?
(Atomic numbers of Mn = 25 and Fe = 26)
Trivalent Lanthanoid ions such as La3+ (Z = 57) and Lu3+ (Z = 71) do not show any colour in their solution. Give a reason.
Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
