about oxidising problem ???

Oxidizing means taking away oxygen ions from another compound.
It occurs in many daily reactions we know,
such as our stomach oxidizes food to release energy every day.
There are various oxidizing agent in the Earth.
Each of them has different oxidizing power,
that means the ability to take away oxygen ions from other compound.
The oxidizing power of the agent affect the progress.
For instance, hydrogen has a neutral oxidzing power which will not easily take away others' oxygen ions and also to reduce(giving out oxygen ions to the others) the other compunds.
If you put two different oxidizing agent separately with a reducing agent,
the one with higher oxidizing power will carry out oxidation much vigorously