MCQ
Which is correct statement?
- ASchottky defect occurs when radius of cation is smaller
- ✓When temperature increases then number of defects decreases
- CFrenkel defect occurs when radius of cation is smaller
- DNone of these
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Reason : Oxygen is bluish coloured liquid and in singlet state it is para-magentic.

(Atomic numbers $Ce =58, Gd =64$ and $Eu =63 .)$
$(a)$ $\left( NH _{4}\right)_{2}\left[ Ce \left( NO _{3}\right)_{6}\right]$
$(b)$ $Gd \left( NO _{3}\right)_{3}$ and
$(c)$ $Eu \left( NO _{3}\right)_{3}$
Answer is :