MCQ
Which lanthanide compound is used as a pigment?
- ✓$ \mathrm{CeO}_2 $
- B$ \mathrm{Ce}(\mathrm{OH})_3 $
- C$ \mathrm{Lu}(\mathrm{OH})_3 $
- D$ \mathrm{\sim Tb}(\mathrm{OH})_3 $
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Assertion $(A)$: There is a considerable increase in covalent radius from $\mathrm{N}$ to $\mathrm{P}$. However from $As$ to $Bi$ only a small increase in covalent radius is observed.
Reason $(R)$: covalent and ionic radii in a particular oxidation state increases down the group.
In the light of the above statement, choose the most appropriate answer from the options given below: