No. it can't be fractional.
However you can get fractional answers uch as Fe in Fe3O4 where the average oxidation state is 2.666.... You need to know something about the structure that will tell you what oxidation numbers of the Fe in this case two Fe with +3 and one Fe with +2 in each formula unit.
8
For Mg the oxidation no is +2 while it is -2 for oxygen.
Hydrogen it depends on the other element if it is part of a compound
The oxidation number of an element depend on another element it react with to form a compound e.g manganese(iv)oxide mno4 the oxidation number of oxygen there is four while the oxidation number of manganse is 7 in most radox reaction the oxidation number of oxygen is usually 4 when writing the full equation
Chromium is a useful element. It shows +2 in this compound.
Oxidation Number
8
For Mg the oxidation no is +2 while it is -2 for oxygen.
In chemistry, the oxidation state is a number assigned to an element as an indicator of the degree of oxidation of an atom in a chemical compound."The charge an element would have if it were an ion "Oxidation state is the same as the oxidation number. It is an indicator of the degree of oxidation of an atom in a chemical compound.
This is not an existing compound, manganese cannot attain the oxidation number +VIII.
Hydrogen it depends on the other element if it is part of a compound
oxidation number
The hydrogen atoms are each in the 1+ oxidation state. The oxygen is in it's 2- oxidation state.
The oxidation number of an element depend on another element it react with to form a compound e.g manganese(iv)oxide mno4 the oxidation number of oxygen there is four while the oxidation number of manganse is 7 in most radox reaction the oxidation number of oxygen is usually 4 when writing the full equation
Chromium is a useful element. It shows +2 in this compound.
There is no compound by the formula PO. There is element, polonium with the symbol, Po, and in elemental form, Po has zero oxidation state.
In the compound Co2O3 cobalt has an oxidation number of 3 while oxygen has an oxidation number is -2.