Question

Which of the following is(are) coloured and paramagnetic?

• A. $K{O}_2$
• B. $K_2{O}_3$
• C. Both (a) and (b)
• D. None of these

Answer 1

The correct option is C Both (a) and (b)

Seaquoxides "$M_2{O}_3$" have been prepared as dark-coloured paramagnetic powders by careful thermal decomposition of $M{O}_2(K,Rb,Cs)$. They can also be obtained by oxidation of liquid ammonia solutions of the metals or by controlled oxidation of the peroxides, $\left[\right(M^{+}{)}_4\left(O_2^{2-}\right)\left(O_2^{-}{)}_2\right]$.

$K{O}_2$ is paramagnetic due to $O_2^{-}$ and is yellow.

which has one unpaired electron so it is paramagnetic. (MOT diagram)

Hence, the correct option is $C$