2KClO3 - 2KCl + 3O2 is formed ! now which kind of reaction is this ? and how can i say it is that particular reaction took place here?

Answer 1

Hint:
the four major types of chemical reactions are:
decomposition
synthesis
substitution or single substitution
methathesis or double substition

For further hints, justifications and detailed explanations, review your class notes, or see:
http://www2.ucdsb.on.ca/tiss/stretton/chem1/stoich2.html