A halogen 'X' forms only one oxoacid and does not exhibit any positive oxidation states. Furthermore, it reacts readily with water to produce oxygen gas. Identify the halogen 'X' and the primary reason it cannot exhibit positive oxidation states like +3, +5 , and +7 .

Step-by-step solution

The halogen 'X' is fluorine. Fluorine is the most electronegative element and reacts with water to oxidize it to oxygen gas. It forms only one oxoacid, HOF (hypofluorous acid). Unlike other halogens (chlorine, bromine, and iodine) which can expand their octet to show +3, +5 , and +7 oxidation states, fluorine is restricted to a -1 oxidation state. This restriction is primarily due to the absence of vacant d-orbitals in its valence shell, which prevents the promotion of electrons and expansion of its covalency. Whil