Question: On combustion of $\mathrm{Li}, \mathrm{Na}$ and $\mathrm{K}$ in excess of air, the major oxides formed, respectively, are :
$\mathrm{Li}_{2} \mathrm{O}_{2}, \mathrm{Na}_{2} \mathrm{O}_{2}$ and $\mathrm{K}_{2} \mathrm{O}_{2}$ (2)
$\mathrm{Li}_{2} \mathrm{O}, \mathrm{Na}_{2} \mathrm{O}_{2}$ and $\mathrm{KO}_{2}$
$\mathrm{Li}_{2} \mathrm{O}, \mathrm{Na}_{2} \mathrm{O}$ and $\mathrm{K}_{2} \mathrm{O}_{2}$
$\mathrm{Li}_{2} \mathrm{O}, \mathrm{Na}_{2} \mathrm{O}_{2}$ and $\mathrm{K}_{2} \mathrm{O}$
Correct Option: , 2
Solution:
On heating in excess air Li form oxide sodium form peroxide while $\mathrm{K}, \mathrm{Rb}, \mathrm{Cs}$ form superoxide.
