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Consider the following statements. I. ...

Consider the following statements.
I. `La(OH)_(3)` is the least basic among hydroxides of lanthanides.
II. `Zr^(4+) and Hf^(4+)` possess almost the same ionic radii.
III. `Ce^(4+)` can act as an oxidising agent.
Which of the above are true ?

A

a) (I) and (III)

B

b) (II) and (III)

C

c) (II) Only

D

d) (I) and (II)

Text Solution

Verified by Experts

The correct Answer is:
B
I. The basic character of hydroxides decreases from `La(OH)_(3)` to `Lu(OH)_(3)`. Thus `La(OH)_(3)` is the most basic among lanthanoid hydroxides.
II. `Zr^(4+) and Hf^(4+)` is almost similar in size due to lanthanide contraction.
III. Cerium exhibits +4 oxidation state in aqueous solution and possesses the tendency to attain +3 oxidation state. Therefore `Ce^(4+)` is a good oxidising agent.
`underset("oxidant")(Ce^(4+)) + Fe^(2+) rarr Ce^(3+) + Fe^(3+)`
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