When alkali metals are burnt in an excess of air, they form different major oxygen compounds. Which — s Block Elements Chemistry Question

💡 Solution & Explanation

Lithium forms mainly monoxide ($Li_2O$, diamagnetic), Sodium forms peroxide ($Na_2O_2$, diamagnetic), and Potassium, Rubidium, and Cesium form superoxides ($MO_2$, paramagnetic). $RbO_2$ is a superoxide and possesses an unpaired electron in its $\pi^* 2p$ molecular orbital, making it paramagnetic.