Oxidation numbers
 
1

What is the oxidation state of each element in the following:

 2

Write down the oxidation state of N in the following:

 3

Write down the oxidation state of each element in red:

 4

Use oxidation numbers to work out the formula of the following ions
  a K     a N2O   a NaClO3   a Chlorate (III) with an overall charge of 1-  
  b Br2     b N2O5   b Na2SO3   b Chlorate (VII) with an overall charge of 1-  
  c NH4+     c N2H4   c KMnO4   c Phosphate (III) with an overall charge of 3-  
  d CaF2     d NO3-   d K2MnO4   d Chromate (VI) with an overall charge of 2-  
  e Al2O3     e HNO2   e K2Cr2O7        
  f NO3-                      
  g PO43-