Advertisements
Advertisements
Question
Which among the following pairs of elements is 'not' an example of chemical twins?
Options
Zr and Hf
Nb and Ta
Mo and W
Ta and Re
Solution
Ta and Re
APPEARS IN
RELATED QUESTIONS
Define lanthanoid contraction.
What are lanthanoids?
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.
Compare the chemistry of actinoids with that of lanthanoids with special reference to electronic configuration.
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 is lanthanoid contraction?
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.............
What is meant by Lanthanide contraction? Write the general electronic configuration of inner transition elements.
What is Lanthanoid contraction?
General electronic configuration of actinoids is `(n-2)f^(1-14)(n - 1)d^(0-2)ns^2`.Which of the following actinoids have one electron in 6d orbital?
(i) U (Atomic no. 92)
(ii) Np (Atomic no.93)
(iii) Pu (Atomic no. 94)
(iv) Am (Atomic no. 95)
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+
Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?
On the basis of Lanthanoid contraction, explain the following:
Radii of 4d and 5d block elements.
On the basis of Lanthanoid contraction, explain the following:
Trends in acidic character of lanthanoid oxides.
In lanthanoid the last electron enters (n - 2)f subshell where n is equal to ______.
Zr (Z = 40) and Hf (Z = 72) have similar atomic and ionic radii because of ______.
The lathanide ion that would show colour is ______.
Mischmetal is an alloy consisting mainly of ______.
Write a note on lanthanoids.
State a reason for the following:
La(OH)3 is more basic than Lu(OH)3.
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.
