What is the oxidation number of fluorine in $F_2O$?

In which of the following does phosphorus have an oxidation state of $+3$?

What is the oxidation number of $S$ in $SO_3^{2-}$?

Write the Lewis structure of the $O_2^-$ ion and find out the oxidation state of each oxygen atom. What is the average oxidation state of oxygen in this ion?

Compounds having the highest oxidation state of the central atom act as acids,the lowest ones act as bases,and intermediate oxidation states act as amphoteric. Which one of the following is amphoteric?

In which of the following compounds,does nitrogen exhibit the highest oxidation state?