1.All elements are zero.

2.Charges of ions are their oxidation numbers.

3.All compounds without a net charge are zero.

4.Hydrogen is almost always 1+ when found in a compound.

5.Oxygen is almost always 2- when found in a compound.

6.If a compound has a net charge, the sum of its atoms’ charges must equal the net charge.

1. Calculate Oxidation Number of sulphur in   

2. Calculate Oxidation Number of chlorine in 

3. Calculate Oxidation Number of nitrogen in