13Waise, not in syllabus, rahul,...chod do usey [1]
A li'l info shud be enough-
: Electromagnetic radiation is a form of energy. As such, it may speed up the rate or even make a reaction spontaneous as it provides the particles of the reactants with more energy. This energy is in one way or another stored in the reacting particles (it may break bonds, promote molecules to electronically or vibrationally excited states...) creating intermediate species that react easily.
(Frm - http://www.absoluteastronomy.com/topics/Reaction_rate)