$RbO_2$ means $Rb^+ O^-_2$ and ion. $O^-_2$ ion is super oxide ion. It has 17 electrons and is paramagnetic.
So, the correct answer is (C): Super oxide and paramagnetic
RbO2 is the rubidium superoxide. In this the Rb is present in +1 oxidation state and oxygen is -1.
RbO2 is an unstable and reactive compound that can be formed with the reaction between rubidium and oxygen.
The compound has unpaired electrons therefore they are paramagnetic in nature.
So, the correct answer is (C): Super oxide and paramagnetic
The number of oxygen atoms present in chemical formula of fuming sulphuric acid is _______.