CUET · CHEMISTRY · PYQ PAPER 2023
Answer the question on the basis of passage given below:
In the periodic table, the d-block contains the elements of group \(3\) to \(12\). The d-orbitals are progressively filled in each of the four long periods. The elements of d block referred as transition metals have partly filled d orbitals and exhibit certain characteristic properties such as variety of oxidation states, formation of coloured ions, act as catalyst and show paramagnetic behaviour.
The two inner transition metals series \(4f\) and \(5f\) are known as Lanthanoids and Actinoids respectively. The lanthanoids resemble one another more closely as compared to ordinary transition elements in any series.
In context of the Lanthanoids, which of the following statements is/are NOT correct?
A. There is a gradual decrease in the radii of the members with increasing atomic number in the series
B. Availability of \(4f\) electrons results in the formation of compounds in \(+4\) oxidation state for all the members of the series
C. Because of similar properties, the separation of lanthanoids is not easy
D. \(La(OH)_3\) is least basic among hydroxides of lanthanoids
E. Ce can act as an oxidising agent
Choose the correct answer from the options given below:
- A A and E only
- B B and D only
- C C and D only
- D B and E only
Answer & Solution
Correct Answer
(B) B and D only
Step-by-step Solution
Detailed explanation
Statement B is NOT correct. Not all lanthanoids form compounds in the \(+4\) oxidation state; the predominant oxidation state is \(+3\). Statement D is NOT correct. \(La(OH)_3\) is the most basic among lanthanoid hydroxides due to the largest ionic radius of \(La^{3+}\). The…
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