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प्रश्न
Which among the following pairs of elements is 'not' an example of chemical twins?
विकल्प
Zr and Hf
Nb and Ta
Mo and W
Ta and Re
उत्तर
Ta and Re
APPEARS IN
संबंधित प्रश्न
Define lanthanoid contraction.
What are chemical twins? Write ‘two’ examples.
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.
Name the members of the lanthanoid series which exhibit +4 oxidation state and those which exhibit +2 oxidation state. Try to correlate this type of behavior with the electronic configurations of these elements.
What are the consequences of lanthanoid contraction?
Answer the followiiig questions:
Which trivalent ion has maximum size in the Lanthanoid series i.e. Lanthanum ion (La3+) to Luteium ion (Lu3+)?
(at. no. of Lanthanum = 57 and Lutetium = 71)
Name an element of lanthanoid series which is well knwon to shown +4 oxidation state. Is it a strong oxidising agent or reducing agent?
What is Lanthanoid contraction?
Gadolinium belongs to 4f series. It’s atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?
Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?
Match the compounds/elements given in Column I with uses given in Column II.
| 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 |
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 \[\ce{Lu2O3}\] .
On the basis of Lanthanoid contraction, explain the following:
Trends in the stability of oxo salts of lanthanoids from \[\ce{La}\] to \[\ce{Lu}\].
On the basis of Lanthanoid contraction, explain the following:
Stability of the complexes of lanthanoids.
On the basis of Lanthanoid contraction, explain the following:
Trends in acidic character of lanthanoid oxides.
The titanium (Z = 22) compound that does not exist is:-
Zr (Z = 40) and Hf (Z = 72) have similar atomic and ionic radii because of ______.
Write any two consequences of Lanthanoid Contraction.
The lathanide ion that would show colour is ______.
Which one of the lanthanoids given below is the most stable in divalent form?
Write a note on lanthanoids.
State a reason for the following:
La(OH)3 is more basic than Lu(OH)3.
Name an important alloy which contains some of the lanthanoid metals.
