Because they are not on the periodic tsble they are on the back and they goes together
The answer is (3) metallic. Cobalt is a transition metal, so it can't be covalent bonds, which bond non-metals, therefore eliminating choice 1 and 2. Ionic bonds are between metals and non metals, but solid cobalt does not have a non metal, eliminating choice 4 as well. Metallic bonds are bonds between metals, therefore the answer is (3) metallic.
the compounds in which phosphorous posses the highest possible oxidation have to mention here.
The species in which phosphorous have the highest oxidation state are: H₃PO₄, P₂O₅, PCl₅
The possible oxidation state of phosphorous is III and V. The highest oxidation state is V. There are several compounds in which phosphorous posses the +5 oxidation state. Like- Phosphoric acid (H₃PO₄), phosphorous pentoxide (P₂O₅), Phosphorous chloride (PCl₅) etc.
The oxidation state of an element depends upon the valence electron the valence shell of phosphorous is 3s² 3p³. Thus there are 5 electrons, as it has vacant 3d orbital thus it can easily form compound having +5 oxidation state.
